From 49d6100183fbdf790be6c8c9f97bf9ceb429b19f Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Mon, 22 Jul 2019 16:39:44 +0300
Subject: [PATCH 01/25] API Core: simplify methods

Two similar methods combined into one.
---
 api_core/google/api_core/datetime_helpers.py | 70 +++++++++++---------
 api_core/tests/unit/test_datetime_helpers.py | 24 ++-----
 2 files changed, 45 insertions(+), 49 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 84c1bb7f512c..be7e8ebbafae 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -17,6 +17,7 @@
 import calendar
 import datetime
 import re
+import warnings
 
 import pytz
 
@@ -115,58 +116,67 @@ def from_iso8601_time(value):
 
 
 def from_rfc3339(value):
-    """Convert a microsecond-precision timestamp to datetime.
+    """Convert a nanosecond-precision or if nanoseconds are missing
+    microsecond-precision timestamp to a native datetime.
+
+    .. note::
+        Python datetimes do not support nanosecond precision; this function
+        therefore truncates such values to microseconds.
 
     Args:
-        value (str): The RFC3339 string to convert.
+        value (str): The RFC 3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the timestamp in
-            UTC.
+        datetime.datetime: The datetime object equivalent to the timestamp
+        in UTC.
+
     """
-    return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    with_nanos = _RFC3339_NANOS.match(value)
+
+    if with_nanos is None:
+        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    else:
+        bare_seconds = datetime.datetime.strptime(
+            with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+        )
+        fraction = with_nanos.group("nanos")
+
+        if fraction is None:
+            micros = 0
+        else:
+            scale = 9 - len(fraction)
+            nanos = int(fraction) * (10 ** scale)
+            micros = nanos // 1000
+
+        return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
 
 
 def from_rfc3339_nanos(value):
     """Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
-        Python datetimes do not support nanosecond precision; this function
-        therefore truncates such values to microseconds.
+        Python datetimes do not support nanosecond precision; this 
+        function therefore truncates such values to microseconds.
 
     Args:
         value (str): The RFC3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the timestamp in
-            UTC.
+        datetime.datetime: The datetime object equivalent to the 
+        timestamp in UTC.
 
     Raises:
         ValueError: If the timestamp does not match the RFC 3339
             regular expression.
     """
-    with_nanos = _RFC3339_NANOS.match(value)
-
-    if with_nanos is None:
-        raise ValueError(
-            "Timestamp: {!r}, does not match pattern: {!r}".format(
-                value, _RFC3339_NANOS.pattern
-            )
-        )
-
-    bare_seconds = datetime.datetime.strptime(
-        with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+    # Raise deprecation warnings for things we want to go away.
+    warnings.warn(
+        "The `from_rfc3339_nanos` method will be deprecated in"
+        "future versions; use `from_rfc3339` instead.",
+        PendingDeprecationWarning,
+        stacklevel=2,
     )
-    fraction = with_nanos.group("nanos")
-
-    if fraction is None:
-        micros = 0
-    else:
-        scale = 9 - len(fraction)
-        nanos = int(fraction) * (10 ** scale)
-        micros = nanos // 1000
-
-    return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
+    return from_rfc3339(value)
 
 
 def to_rfc3339(value, ignore_zone=True):
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 4d138c88a80c..fb615a5c872d 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -83,33 +83,19 @@ def test_from_rfc3339():
 
 
 def test_from_rfc3339_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339(value)
-
-
-def test_from_rfc3339_with_nanos():
-    value = "2009-12-17T12:44:32.123456789Z"
+    value = "2009-12-17T12:44:32.123456789BAD"
 
     with pytest.raises(ValueError):
         datetime_helpers.from_rfc3339(value)
 
 
-def test_from_rfc3339_nanos_without_nanos():
+def test_from_rfc3339_without_nanos():
     value = "2009-12-17T12:44:32Z"
-    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+    assert datetime_helpers.from_rfc3339(value) == datetime.datetime(
         2009, 12, 17, 12, 44, 32, 0, pytz.utc
     )
 
 
-def test_from_rfc3339_nanos_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456789BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339_nanos(value)
-
-
 @pytest.mark.parametrize(
     "truncated, micros",
     [
@@ -123,9 +109,9 @@ def test_from_rfc3339_nanos_with_bad_tz():
         ("1", 100000),
     ],
 )
-def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
+def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     value = "2009-12-17T12:44:32.{}Z".format(truncated)
-    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+    assert datetime_helpers.from_rfc3339(value) == datetime.datetime(
         2009, 12, 17, 12, 44, 32, micros, pytz.utc
     )
 

From ddbcb99573431b00b7dc1de361f4fd73cdd40d96 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Wed, 24 Jul 2019 12:25:22 +0300
Subject: [PATCH 02/25] Update test_datetime_helpers.py

Re-write tests for the 'from_rfc3339_nanos' method.
---
 api_core/tests/unit/test_datetime_helpers.py | 37 +++++++++++++++++---
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index fb615a5c872d..e06daf88bfcb 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -82,11 +82,11 @@ def test_from_rfc3339():
     )
 
 
-def test_from_rfc3339_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456789BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339(value)
+def test_from_rfc3339_nanos():
+    value = "2009-12-17T12:44:32.123456Z"
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, 123456, pytz.utc
+    )
 
 
 def test_from_rfc3339_without_nanos():
@@ -96,6 +96,13 @@ def test_from_rfc3339_without_nanos():
     )
 
 
+def test_from_rfc3339_nanos_without_nanos():
+    value = "2009-12-17T12:44:32Z"
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, 0, pytz.utc
+    )
+
+
 @pytest.mark.parametrize(
     "truncated, micros",
     [
@@ -116,6 +123,26 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     )
 
 
+@pytest.mark.parametrize(
+    "truncated, micros",
+    [
+        ("12345678", 123456),
+        ("1234567", 123456),
+        ("123456", 123456),
+        ("12345", 123450),
+        ("1234", 123400),
+        ("123", 123000),
+        ("12", 120000),
+        ("1", 100000),
+    ],
+)
+def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
+    value = "2009-12-17T12:44:32.{}Z".format(truncated)
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, micros, pytz.utc
+    )
+
+
 def test_to_rfc3339():
     value = datetime.datetime(2016, 4, 5, 13, 30, 0)
     expected = "2016-04-05T13:30:00.000000Z"

From 1cfaf618f76e654c8aabc081cbbe538aeed128dd Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Thu, 25 Jul 2019 13:13:25 +0300
Subject: [PATCH 03/25] Update datetime_helpers.py

Fix for coverage and lint failures.
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index be7e8ebbafae..c01c9c067af7 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -131,11 +131,11 @@ def from_rfc3339(value):
         in UTC.
 
     """
-    with_nanos = _RFC3339_NANOS.match(value)
-
-    if with_nanos is None:
+    try:
         return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
-    else:
+    except ValueError:
+        with_nanos = _RFC3339_NANOS.match(value)
+
         bare_seconds = datetime.datetime.strptime(
             with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
         )
@@ -155,14 +155,14 @@ def from_rfc3339_nanos(value):
     """Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
-        Python datetimes do not support nanosecond precision; this 
+        Python datetimes do not support nanosecond precision; this
         function therefore truncates such values to microseconds.
 
     Args:
         value (str): The RFC3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the 
+        datetime.datetime: The datetime object equivalent to the
         timestamp in UTC.
 
     Raises:
@@ -172,7 +172,7 @@ def from_rfc3339_nanos(value):
     # Raise deprecation warnings for things we want to go away.
     warnings.warn(
         "The `from_rfc3339_nanos` method will be deprecated in"
-        "future versions; use `from_rfc3339` instead.",
+        " future versions; use `from_rfc3339` instead.",
         PendingDeprecationWarning,
         stacklevel=2,
     )

From 59a49b944751dace4e3a0096b84acfb9378a6832 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 10:22:47 +0300
Subject: [PATCH 04/25] Update datetime_helpers.py

restore previous version with testing regex first + cosmetic chgs for the descriptions
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index c01c9c067af7..476110668658 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -131,11 +131,11 @@ def from_rfc3339(value):
         in UTC.
 
     """
-    try:
-        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
-    except ValueError:
-        with_nanos = _RFC3339_NANOS.match(value)
+    with_nanos = _RFC3339_NANOS.match(value)
 
+    if with_nanos is None:
+        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    else:
         bare_seconds = datetime.datetime.strptime(
             with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
         )
@@ -152,7 +152,7 @@ def from_rfc3339(value):
 
 
 def from_rfc3339_nanos(value):
-    """Convert a nanosecond-precision timestamp to a native datetime.
+    """DEPRECATED. Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
         Python datetimes do not support nanosecond precision; this
@@ -171,8 +171,8 @@ def from_rfc3339_nanos(value):
     """
     # Raise deprecation warnings for things we want to go away.
     warnings.warn(
-        "The `from_rfc3339_nanos` method will be deprecated in"
-        " future versions; use `from_rfc3339` instead.",
+        "The `from_rfc3339_nanos` function is deprecated"
+        " use `from_rfc3339` instead.",
         PendingDeprecationWarning,
         stacklevel=2,
     )

From 0481ad45b311573a221cd52d34d9c14e1a672432 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 15:07:35 +0300
Subject: [PATCH 05/25] Update test_datetime_helpers.py

added test to check the deprecation warning
---
 api_core/tests/unit/test_datetime_helpers.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index e06daf88bfcb..c1096cc914a6 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -15,6 +15,7 @@
 import calendar
 import datetime
 
+import mock
 import pytest
 import pytz
 
@@ -23,6 +24,8 @@
 
 
 ONE_MINUTE_IN_MICROSECONDS = 60 * 1e6
+MESSAGE = ("The `from_rfc3339_nanos` function is deprecated"
+           " use `from_rfc3339` instead.")
 
 
 def test_utcnow():
@@ -123,6 +126,19 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     )
 
 
+def test_from_rfc3339_nanos_is_deprecated():
+    from_rfc3339_patch = mock.patch("google.api_core.datetime_helpers.from_rfc3339")
+    warnings_patch = mock.patch("warnings.warn")
+    value = "2009-12-17T12:44:32.123456Z"
+
+    with from_rfc3339_patch as from_rfc3339, warnings_patch as warn:
+        result = datetime_helpers.from_rfc3339_nanos(value)
+
+    assert result is from_rfc3339.return_value
+    from_rfc3339.assert_called_once_with(value)
+    warn.assert_called_once_with(MESSAGE, DeprecationWarning, stacklevel=2)
+
+
 @pytest.mark.parametrize(
     "truncated, micros",
     [

From 710978bf70a4c7e6a374d7080b8bc904fa1dd660 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 15:09:28 +0300
Subject: [PATCH 06/25] Update datetime_helpers.py

adjusted the condition for the 'from_rfc3339' method + warning fix
---
 api_core/google/api_core/datetime_helpers.py | 26 +++++++++-----------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 476110668658..4368df89c3b5 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -132,23 +132,19 @@ def from_rfc3339(value):
 
     """
     with_nanos = _RFC3339_NANOS.match(value)
+    bare_seconds = datetime.datetime.strptime(
+        with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+    )
+    fraction = with_nanos.group("nanos")
 
-    if with_nanos is None:
-        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    if fraction is None:
+        micros = 0
     else:
-        bare_seconds = datetime.datetime.strptime(
-            with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
-        )
-        fraction = with_nanos.group("nanos")
-
-        if fraction is None:
-            micros = 0
-        else:
-            scale = 9 - len(fraction)
-            nanos = int(fraction) * (10 ** scale)
-            micros = nanos // 1000
+        scale = 9 - len(fraction)
+        nanos = int(fraction) * (10 ** scale)
+        micros = nanos // 1000
 
-        return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
+    return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
 
 
 def from_rfc3339_nanos(value):
@@ -173,7 +169,7 @@ def from_rfc3339_nanos(value):
     warnings.warn(
         "The `from_rfc3339_nanos` function is deprecated"
         " use `from_rfc3339` instead.",
-        PendingDeprecationWarning,
+        DeprecationWarning,
         stacklevel=2,
     )
     return from_rfc3339(value)

From 70bf8bcafee5ad64a1a6268ef2177324d3c79071 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 23 Aug 2019 10:56:38 +0300
Subject: [PATCH 07/25] Update datetime_helpers.py

* deleted extra spaces
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 4368df89c3b5..310240f4d4b7 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -124,7 +124,7 @@ def from_rfc3339(value):
         therefore truncates such values to microseconds.
 
     Args:
-        value (str): The RFC 3339 string to convert.
+        value (str): The RFC3339 string to convert.
 
     Returns:
         datetime.datetime: The datetime object equivalent to the timestamp
@@ -162,7 +162,7 @@ def from_rfc3339_nanos(value):
         timestamp in UTC.
 
     Raises:
-        ValueError: If the timestamp does not match the RFC 3339
+        ValueError: If the timestamp does not match the RFC3339
             regular expression.
     """
     # Raise deprecation warnings for things we want to go away.
@@ -221,10 +221,10 @@ def nanosecond(self):
         return self._nanosecond
 
     def rfc3339(self):
-        """Return an RFC 3339-compliant timestamp.
+        """Return an RFC3339-compliant timestamp.
 
         Returns:
-            (str): Timestamp string according to RFC 3339 spec.
+            (str): Timestamp string according to RFC3339 spec.
         """
         if self._nanosecond == 0:
             return to_rfc3339(self)
@@ -233,10 +233,10 @@ def rfc3339(self):
 
     @classmethod
     def from_rfc3339(cls, stamp):
-        """Parse RFC 3339-compliant timestamp, preserving nanoseconds.
+        """Parse RFC3339-compliant timestamp, preserving nanoseconds.
 
         Args:
-            stamp (str): RFC 3339 stamp, with up to nanosecond precision
+            stamp (str): RFC3339 stamp, with up to nanosecond precision
 
         Returns:
             :class:`DatetimeWithNanoseconds`:
@@ -286,7 +286,7 @@ def timestamp_pb(self):
 
     @classmethod
     def from_timestamp_pb(cls, stamp):
-        """Parse RFC 3339-compliant timestamp, preserving nanoseconds.
+        """Parse RFC3339-compliant timestamp, preserving nanoseconds.
 
         Args:
             stamp (:class:`~google.protobuf.timestamp_pb2.Timestamp`): timestamp message

From 06bee67b097e485a58415d218f3ac421a04d3d6a Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Thu, 5 Sep 2019 20:52:35 +0300
Subject: [PATCH 08/25] update datetime_helpers

* 'if-else' statement restored to throw an exception
* wrote additional tests to cover the exception
---
 api_core/google/api_core/datetime_helpers.py | 10 ++++-
 api_core/tests/unit/test_datetime_helpers.py | 43 ++++++++++++++------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 310240f4d4b7..9bc6a910974b 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -132,6 +132,14 @@ def from_rfc3339(value):
 
     """
     with_nanos = _RFC3339_NANOS.match(value)
+
+    if with_nanos is None:
+        raise ValueError(
+            "Timestamp: {!r}, does not match pattern: {!r}".format(
+                value, _RFC3339_NANOS.pattern
+            )
+        )
+
     bare_seconds = datetime.datetime.strptime(
         with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
     )
@@ -228,7 +236,7 @@ def rfc3339(self):
         """
         if self._nanosecond == 0:
             return to_rfc3339(self)
-        nanos = str(self._nanosecond).rjust(9, '0').rstrip("0")
+        nanos = str(self._nanosecond).rjust(9, "0").rstrip("0")
         return "{}.{}Z".format(self.strftime(_RFC3339_NO_FRACTION), nanos)
 
     @classmethod
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index c1096cc914a6..948723f96ead 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -24,8 +24,9 @@
 
 
 ONE_MINUTE_IN_MICROSECONDS = 60 * 1e6
-MESSAGE = ("The `from_rfc3339_nanos` function is deprecated"
-           " use `from_rfc3339` instead.")
+MESSAGE = (
+    "The `from_rfc3339_nanos` function is deprecated" " use `from_rfc3339` instead."
+)
 
 
 def test_utcnow():
@@ -159,6 +160,18 @@ def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
     )
 
 
+def test_from_rfc3339_wo_nanos_raise_exception():
+    value = "2009-12-17T12:44:32"
+    with pytest.raises(ValueError):
+        datetime_helpers.from_rfc3339(value)
+
+
+def test_from_rfc3339_w_nanos_raise_exception():
+    value = "2009-12-17T12:44:32.123456"
+    with pytest.raises(ValueError):
+        datetime_helpers.from_rfc3339(value)
+
+
 def test_to_rfc3339():
     value = datetime.datetime(2016, 4, 5, 13, 30, 0)
     expected = "2016-04-05T13:30:00.000000Z"
@@ -186,10 +199,11 @@ def test_to_rfc3339_with_non_utc_ignore_zone():
 
 
 class Test_DateTimeWithNanos(object):
-
     @staticmethod
     def test_ctor_wo_nanos():
-        stamp = datetime_helpers.DatetimeWithNanoseconds(2016, 12, 20, 21, 13, 47, 123456)
+        stamp = datetime_helpers.DatetimeWithNanoseconds(
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         assert stamp.year == 2016
         assert stamp.month == 12
         assert stamp.day == 20
@@ -229,7 +243,9 @@ def test_ctor_w_micros_keyword_and_nanos():
 
     @staticmethod
     def test_rfc3339_wo_nanos():
-        stamp = datetime_helpers.DatetimeWithNanoseconds(2016, 12, 20, 21, 13, 47, 123456)
+        stamp = datetime_helpers.DatetimeWithNanoseconds(
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         assert stamp.rfc3339() == "2016-12-20T21:13:47.123456Z"
 
     @staticmethod
@@ -314,12 +330,16 @@ def test_from_rfc3339_w_full_precision():
     )
     def test_from_rfc3339_test_nanoseconds(fractional, nanos):
         value = "2009-12-17T12:44:32.{}Z".format(fractional)
-        assert datetime_helpers.DatetimeWithNanoseconds.from_rfc3339(value).nanosecond == nanos
+        assert (
+            datetime_helpers.DatetimeWithNanoseconds.from_rfc3339(value).nanosecond
+            == nanos
+        )
 
     @staticmethod
     def test_timestamp_pb_wo_nanos_naive():
         stamp = datetime_helpers.DatetimeWithNanoseconds(
-            2016, 12, 20, 21, 13, 47, 123456)
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         delta = stamp.replace(tzinfo=pytz.UTC) - datetime_helpers._UTC_EPOCH
         seconds = int(delta.total_seconds())
         nanos = 123456000
@@ -333,7 +353,8 @@ def test_timestamp_pb_w_nanos():
         )
         delta = stamp - datetime_helpers._UTC_EPOCH
         timestamp = timestamp_pb2.Timestamp(
-            seconds=int(delta.total_seconds()), nanos=123456789)
+            seconds=int(delta.total_seconds()), nanos=123456789
+        )
         assert stamp.timestamp_pb() == timestamp
 
     @staticmethod
@@ -343,8 +364,7 @@ def test_from_timestamp_pb_wo_nanos():
         seconds = int(delta.total_seconds())
         timestamp = timestamp_pb2.Timestamp(seconds=seconds)
 
-        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(
-            timestamp)
+        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(timestamp)
 
         assert _to_seconds(when) == _to_seconds(stamp)
         assert stamp.microsecond == 0
@@ -358,8 +378,7 @@ def test_from_timestamp_pb_w_nanos():
         seconds = int(delta.total_seconds())
         timestamp = timestamp_pb2.Timestamp(seconds=seconds, nanos=123456789)
 
-        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(
-            timestamp)
+        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(timestamp)
 
         assert _to_seconds(when) == _to_seconds(stamp)
         assert stamp.microsecond == 123456

From 873a60dbc64b4ae3ef585f289d25eade0369ea72 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Mon, 22 Jul 2019 16:39:44 +0300
Subject: [PATCH 09/25] API Core: simplify methods

Two similar methods combined into one.
---
 api_core/google/api_core/datetime_helpers.py | 70 +++++++++++---------
 api_core/tests/unit/test_datetime_helpers.py | 24 ++-----
 2 files changed, 45 insertions(+), 49 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 84c1bb7f512c..be7e8ebbafae 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -17,6 +17,7 @@
 import calendar
 import datetime
 import re
+import warnings
 
 import pytz
 
@@ -115,58 +116,67 @@ def from_iso8601_time(value):
 
 
 def from_rfc3339(value):
-    """Convert a microsecond-precision timestamp to datetime.
+    """Convert a nanosecond-precision or if nanoseconds are missing
+    microsecond-precision timestamp to a native datetime.
+
+    .. note::
+        Python datetimes do not support nanosecond precision; this function
+        therefore truncates such values to microseconds.
 
     Args:
-        value (str): The RFC3339 string to convert.
+        value (str): The RFC 3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the timestamp in
-            UTC.
+        datetime.datetime: The datetime object equivalent to the timestamp
+        in UTC.
+
     """
-    return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    with_nanos = _RFC3339_NANOS.match(value)
+
+    if with_nanos is None:
+        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    else:
+        bare_seconds = datetime.datetime.strptime(
+            with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+        )
+        fraction = with_nanos.group("nanos")
+
+        if fraction is None:
+            micros = 0
+        else:
+            scale = 9 - len(fraction)
+            nanos = int(fraction) * (10 ** scale)
+            micros = nanos // 1000
+
+        return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
 
 
 def from_rfc3339_nanos(value):
     """Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
-        Python datetimes do not support nanosecond precision; this function
-        therefore truncates such values to microseconds.
+        Python datetimes do not support nanosecond precision; this 
+        function therefore truncates such values to microseconds.
 
     Args:
         value (str): The RFC3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the timestamp in
-            UTC.
+        datetime.datetime: The datetime object equivalent to the 
+        timestamp in UTC.
 
     Raises:
         ValueError: If the timestamp does not match the RFC 3339
             regular expression.
     """
-    with_nanos = _RFC3339_NANOS.match(value)
-
-    if with_nanos is None:
-        raise ValueError(
-            "Timestamp: {!r}, does not match pattern: {!r}".format(
-                value, _RFC3339_NANOS.pattern
-            )
-        )
-
-    bare_seconds = datetime.datetime.strptime(
-        with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+    # Raise deprecation warnings for things we want to go away.
+    warnings.warn(
+        "The `from_rfc3339_nanos` method will be deprecated in"
+        "future versions; use `from_rfc3339` instead.",
+        PendingDeprecationWarning,
+        stacklevel=2,
     )
-    fraction = with_nanos.group("nanos")
-
-    if fraction is None:
-        micros = 0
-    else:
-        scale = 9 - len(fraction)
-        nanos = int(fraction) * (10 ** scale)
-        micros = nanos // 1000
-
-    return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
+    return from_rfc3339(value)
 
 
 def to_rfc3339(value, ignore_zone=True):
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 4d138c88a80c..fb615a5c872d 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -83,33 +83,19 @@ def test_from_rfc3339():
 
 
 def test_from_rfc3339_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339(value)
-
-
-def test_from_rfc3339_with_nanos():
-    value = "2009-12-17T12:44:32.123456789Z"
+    value = "2009-12-17T12:44:32.123456789BAD"
 
     with pytest.raises(ValueError):
         datetime_helpers.from_rfc3339(value)
 
 
-def test_from_rfc3339_nanos_without_nanos():
+def test_from_rfc3339_without_nanos():
     value = "2009-12-17T12:44:32Z"
-    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+    assert datetime_helpers.from_rfc3339(value) == datetime.datetime(
         2009, 12, 17, 12, 44, 32, 0, pytz.utc
     )
 
 
-def test_from_rfc3339_nanos_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456789BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339_nanos(value)
-
-
 @pytest.mark.parametrize(
     "truncated, micros",
     [
@@ -123,9 +109,9 @@ def test_from_rfc3339_nanos_with_bad_tz():
         ("1", 100000),
     ],
 )
-def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
+def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     value = "2009-12-17T12:44:32.{}Z".format(truncated)
-    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+    assert datetime_helpers.from_rfc3339(value) == datetime.datetime(
         2009, 12, 17, 12, 44, 32, micros, pytz.utc
     )
 

From 796204cb3a8ce747b180e0fbd7bd54408013f037 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Wed, 24 Jul 2019 12:25:22 +0300
Subject: [PATCH 10/25] Update test_datetime_helpers.py

Re-write tests for the 'from_rfc3339_nanos' method.
---
 api_core/tests/unit/test_datetime_helpers.py | 37 +++++++++++++++++---
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index fb615a5c872d..e06daf88bfcb 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -82,11 +82,11 @@ def test_from_rfc3339():
     )
 
 
-def test_from_rfc3339_with_bad_tz():
-    value = "2009-12-17T12:44:32.123456789BAD"
-
-    with pytest.raises(ValueError):
-        datetime_helpers.from_rfc3339(value)
+def test_from_rfc3339_nanos():
+    value = "2009-12-17T12:44:32.123456Z"
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, 123456, pytz.utc
+    )
 
 
 def test_from_rfc3339_without_nanos():
@@ -96,6 +96,13 @@ def test_from_rfc3339_without_nanos():
     )
 
 
+def test_from_rfc3339_nanos_without_nanos():
+    value = "2009-12-17T12:44:32Z"
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, 0, pytz.utc
+    )
+
+
 @pytest.mark.parametrize(
     "truncated, micros",
     [
@@ -116,6 +123,26 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     )
 
 
+@pytest.mark.parametrize(
+    "truncated, micros",
+    [
+        ("12345678", 123456),
+        ("1234567", 123456),
+        ("123456", 123456),
+        ("12345", 123450),
+        ("1234", 123400),
+        ("123", 123000),
+        ("12", 120000),
+        ("1", 100000),
+    ],
+)
+def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
+    value = "2009-12-17T12:44:32.{}Z".format(truncated)
+    assert datetime_helpers.from_rfc3339_nanos(value) == datetime.datetime(
+        2009, 12, 17, 12, 44, 32, micros, pytz.utc
+    )
+
+
 def test_to_rfc3339():
     value = datetime.datetime(2016, 4, 5, 13, 30, 0)
     expected = "2016-04-05T13:30:00.000000Z"

From 0503e92f6eb975c3711455df301e797cee9d6bf2 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Thu, 25 Jul 2019 13:13:25 +0300
Subject: [PATCH 11/25] Update datetime_helpers.py

Fix for coverage and lint failures.
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index be7e8ebbafae..c01c9c067af7 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -131,11 +131,11 @@ def from_rfc3339(value):
         in UTC.
 
     """
-    with_nanos = _RFC3339_NANOS.match(value)
-
-    if with_nanos is None:
+    try:
         return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
-    else:
+    except ValueError:
+        with_nanos = _RFC3339_NANOS.match(value)
+
         bare_seconds = datetime.datetime.strptime(
             with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
         )
@@ -155,14 +155,14 @@ def from_rfc3339_nanos(value):
     """Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
-        Python datetimes do not support nanosecond precision; this 
+        Python datetimes do not support nanosecond precision; this
         function therefore truncates such values to microseconds.
 
     Args:
         value (str): The RFC3339 string to convert.
 
     Returns:
-        datetime.datetime: The datetime object equivalent to the 
+        datetime.datetime: The datetime object equivalent to the
         timestamp in UTC.
 
     Raises:
@@ -172,7 +172,7 @@ def from_rfc3339_nanos(value):
     # Raise deprecation warnings for things we want to go away.
     warnings.warn(
         "The `from_rfc3339_nanos` method will be deprecated in"
-        "future versions; use `from_rfc3339` instead.",
+        " future versions; use `from_rfc3339` instead.",
         PendingDeprecationWarning,
         stacklevel=2,
     )

From dc4f896f7ef5bde0e6c0ecb6e2306d77bafc4877 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 10:22:47 +0300
Subject: [PATCH 12/25] Update datetime_helpers.py

restore previous version with testing regex first + cosmetic chgs for the descriptions
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index c01c9c067af7..476110668658 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -131,11 +131,11 @@ def from_rfc3339(value):
         in UTC.
 
     """
-    try:
-        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
-    except ValueError:
-        with_nanos = _RFC3339_NANOS.match(value)
+    with_nanos = _RFC3339_NANOS.match(value)
 
+    if with_nanos is None:
+        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    else:
         bare_seconds = datetime.datetime.strptime(
             with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
         )
@@ -152,7 +152,7 @@ def from_rfc3339(value):
 
 
 def from_rfc3339_nanos(value):
-    """Convert a nanosecond-precision timestamp to a native datetime.
+    """DEPRECATED. Convert a nanosecond-precision timestamp to a native datetime.
 
     .. note::
         Python datetimes do not support nanosecond precision; this
@@ -171,8 +171,8 @@ def from_rfc3339_nanos(value):
     """
     # Raise deprecation warnings for things we want to go away.
     warnings.warn(
-        "The `from_rfc3339_nanos` method will be deprecated in"
-        " future versions; use `from_rfc3339` instead.",
+        "The `from_rfc3339_nanos` function is deprecated"
+        " use `from_rfc3339` instead.",
         PendingDeprecationWarning,
         stacklevel=2,
     )

From 4bcf6518adb27a6e6e5c10d83cdde558b494f896 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 15:07:35 +0300
Subject: [PATCH 13/25] Update test_datetime_helpers.py

added test to check the deprecation warning
---
 api_core/tests/unit/test_datetime_helpers.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index e06daf88bfcb..c1096cc914a6 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -15,6 +15,7 @@
 import calendar
 import datetime
 
+import mock
 import pytest
 import pytz
 
@@ -23,6 +24,8 @@
 
 
 ONE_MINUTE_IN_MICROSECONDS = 60 * 1e6
+MESSAGE = ("The `from_rfc3339_nanos` function is deprecated"
+           " use `from_rfc3339` instead.")
 
 
 def test_utcnow():
@@ -123,6 +126,19 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
     )
 
 
+def test_from_rfc3339_nanos_is_deprecated():
+    from_rfc3339_patch = mock.patch("google.api_core.datetime_helpers.from_rfc3339")
+    warnings_patch = mock.patch("warnings.warn")
+    value = "2009-12-17T12:44:32.123456Z"
+
+    with from_rfc3339_patch as from_rfc3339, warnings_patch as warn:
+        result = datetime_helpers.from_rfc3339_nanos(value)
+
+    assert result is from_rfc3339.return_value
+    from_rfc3339.assert_called_once_with(value)
+    warn.assert_called_once_with(MESSAGE, DeprecationWarning, stacklevel=2)
+
+
 @pytest.mark.parametrize(
     "truncated, micros",
     [

From 8151cae2d1230880245b651888c2134752cd15a0 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 26 Jul 2019 15:09:28 +0300
Subject: [PATCH 14/25] Update datetime_helpers.py

adjusted the condition for the 'from_rfc3339' method + warning fix
---
 api_core/google/api_core/datetime_helpers.py | 26 +++++++++-----------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 476110668658..4368df89c3b5 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -132,23 +132,19 @@ def from_rfc3339(value):
 
     """
     with_nanos = _RFC3339_NANOS.match(value)
+    bare_seconds = datetime.datetime.strptime(
+        with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
+    )
+    fraction = with_nanos.group("nanos")
 
-    if with_nanos is None:
-        return datetime.datetime.strptime(value, _RFC3339_MICROS).replace(tzinfo=pytz.utc)
+    if fraction is None:
+        micros = 0
     else:
-        bare_seconds = datetime.datetime.strptime(
-            with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
-        )
-        fraction = with_nanos.group("nanos")
-
-        if fraction is None:
-            micros = 0
-        else:
-            scale = 9 - len(fraction)
-            nanos = int(fraction) * (10 ** scale)
-            micros = nanos // 1000
+        scale = 9 - len(fraction)
+        nanos = int(fraction) * (10 ** scale)
+        micros = nanos // 1000
 
-        return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
+    return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
 
 
 def from_rfc3339_nanos(value):
@@ -173,7 +169,7 @@ def from_rfc3339_nanos(value):
     warnings.warn(
         "The `from_rfc3339_nanos` function is deprecated"
         " use `from_rfc3339` instead.",
-        PendingDeprecationWarning,
+        DeprecationWarning,
         stacklevel=2,
     )
     return from_rfc3339(value)

From 447ed3e294ab4a1396728f80390186e9b03dfaa2 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 23 Aug 2019 10:56:38 +0300
Subject: [PATCH 15/25] Update datetime_helpers.py

* deleted extra spaces
---
 api_core/google/api_core/datetime_helpers.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 4368df89c3b5..310240f4d4b7 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -124,7 +124,7 @@ def from_rfc3339(value):
         therefore truncates such values to microseconds.
 
     Args:
-        value (str): The RFC 3339 string to convert.
+        value (str): The RFC3339 string to convert.
 
     Returns:
         datetime.datetime: The datetime object equivalent to the timestamp
@@ -162,7 +162,7 @@ def from_rfc3339_nanos(value):
         timestamp in UTC.
 
     Raises:
-        ValueError: If the timestamp does not match the RFC 3339
+        ValueError: If the timestamp does not match the RFC3339
             regular expression.
     """
     # Raise deprecation warnings for things we want to go away.
@@ -221,10 +221,10 @@ def nanosecond(self):
         return self._nanosecond
 
     def rfc3339(self):
-        """Return an RFC 3339-compliant timestamp.
+        """Return an RFC3339-compliant timestamp.
 
         Returns:
-            (str): Timestamp string according to RFC 3339 spec.
+            (str): Timestamp string according to RFC3339 spec.
         """
         if self._nanosecond == 0:
             return to_rfc3339(self)
@@ -233,10 +233,10 @@ def rfc3339(self):
 
     @classmethod
     def from_rfc3339(cls, stamp):
-        """Parse RFC 3339-compliant timestamp, preserving nanoseconds.
+        """Parse RFC3339-compliant timestamp, preserving nanoseconds.
 
         Args:
-            stamp (str): RFC 3339 stamp, with up to nanosecond precision
+            stamp (str): RFC3339 stamp, with up to nanosecond precision
 
         Returns:
             :class:`DatetimeWithNanoseconds`:
@@ -286,7 +286,7 @@ def timestamp_pb(self):
 
     @classmethod
     def from_timestamp_pb(cls, stamp):
-        """Parse RFC 3339-compliant timestamp, preserving nanoseconds.
+        """Parse RFC3339-compliant timestamp, preserving nanoseconds.
 
         Args:
             stamp (:class:`~google.protobuf.timestamp_pb2.Timestamp`): timestamp message

From 1fc8661cc3ea18de692370c476c2bf77873bff7a Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Thu, 5 Sep 2019 20:52:35 +0300
Subject: [PATCH 16/25] update datetime_helpers

* 'if-else' statement restored to throw an exception
* wrote additional tests to cover the exception
---
 api_core/google/api_core/datetime_helpers.py | 10 ++++-
 api_core/tests/unit/test_datetime_helpers.py | 43 ++++++++++++++------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 310240f4d4b7..9bc6a910974b 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -132,6 +132,14 @@ def from_rfc3339(value):
 
     """
     with_nanos = _RFC3339_NANOS.match(value)
+
+    if with_nanos is None:
+        raise ValueError(
+            "Timestamp: {!r}, does not match pattern: {!r}".format(
+                value, _RFC3339_NANOS.pattern
+            )
+        )
+
     bare_seconds = datetime.datetime.strptime(
         with_nanos.group("no_fraction"), _RFC3339_NO_FRACTION
     )
@@ -228,7 +236,7 @@ def rfc3339(self):
         """
         if self._nanosecond == 0:
             return to_rfc3339(self)
-        nanos = str(self._nanosecond).rjust(9, '0').rstrip("0")
+        nanos = str(self._nanosecond).rjust(9, "0").rstrip("0")
         return "{}.{}Z".format(self.strftime(_RFC3339_NO_FRACTION), nanos)
 
     @classmethod
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index c1096cc914a6..948723f96ead 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -24,8 +24,9 @@
 
 
 ONE_MINUTE_IN_MICROSECONDS = 60 * 1e6
-MESSAGE = ("The `from_rfc3339_nanos` function is deprecated"
-           " use `from_rfc3339` instead.")
+MESSAGE = (
+    "The `from_rfc3339_nanos` function is deprecated" " use `from_rfc3339` instead."
+)
 
 
 def test_utcnow():
@@ -159,6 +160,18 @@ def test_from_rfc3339_nanos_with_truncated_nanos(truncated, micros):
     )
 
 
+def test_from_rfc3339_wo_nanos_raise_exception():
+    value = "2009-12-17T12:44:32"
+    with pytest.raises(ValueError):
+        datetime_helpers.from_rfc3339(value)
+
+
+def test_from_rfc3339_w_nanos_raise_exception():
+    value = "2009-12-17T12:44:32.123456"
+    with pytest.raises(ValueError):
+        datetime_helpers.from_rfc3339(value)
+
+
 def test_to_rfc3339():
     value = datetime.datetime(2016, 4, 5, 13, 30, 0)
     expected = "2016-04-05T13:30:00.000000Z"
@@ -186,10 +199,11 @@ def test_to_rfc3339_with_non_utc_ignore_zone():
 
 
 class Test_DateTimeWithNanos(object):
-
     @staticmethod
     def test_ctor_wo_nanos():
-        stamp = datetime_helpers.DatetimeWithNanoseconds(2016, 12, 20, 21, 13, 47, 123456)
+        stamp = datetime_helpers.DatetimeWithNanoseconds(
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         assert stamp.year == 2016
         assert stamp.month == 12
         assert stamp.day == 20
@@ -229,7 +243,9 @@ def test_ctor_w_micros_keyword_and_nanos():
 
     @staticmethod
     def test_rfc3339_wo_nanos():
-        stamp = datetime_helpers.DatetimeWithNanoseconds(2016, 12, 20, 21, 13, 47, 123456)
+        stamp = datetime_helpers.DatetimeWithNanoseconds(
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         assert stamp.rfc3339() == "2016-12-20T21:13:47.123456Z"
 
     @staticmethod
@@ -314,12 +330,16 @@ def test_from_rfc3339_w_full_precision():
     )
     def test_from_rfc3339_test_nanoseconds(fractional, nanos):
         value = "2009-12-17T12:44:32.{}Z".format(fractional)
-        assert datetime_helpers.DatetimeWithNanoseconds.from_rfc3339(value).nanosecond == nanos
+        assert (
+            datetime_helpers.DatetimeWithNanoseconds.from_rfc3339(value).nanosecond
+            == nanos
+        )
 
     @staticmethod
     def test_timestamp_pb_wo_nanos_naive():
         stamp = datetime_helpers.DatetimeWithNanoseconds(
-            2016, 12, 20, 21, 13, 47, 123456)
+            2016, 12, 20, 21, 13, 47, 123456
+        )
         delta = stamp.replace(tzinfo=pytz.UTC) - datetime_helpers._UTC_EPOCH
         seconds = int(delta.total_seconds())
         nanos = 123456000
@@ -333,7 +353,8 @@ def test_timestamp_pb_w_nanos():
         )
         delta = stamp - datetime_helpers._UTC_EPOCH
         timestamp = timestamp_pb2.Timestamp(
-            seconds=int(delta.total_seconds()), nanos=123456789)
+            seconds=int(delta.total_seconds()), nanos=123456789
+        )
         assert stamp.timestamp_pb() == timestamp
 
     @staticmethod
@@ -343,8 +364,7 @@ def test_from_timestamp_pb_wo_nanos():
         seconds = int(delta.total_seconds())
         timestamp = timestamp_pb2.Timestamp(seconds=seconds)
 
-        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(
-            timestamp)
+        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(timestamp)
 
         assert _to_seconds(when) == _to_seconds(stamp)
         assert stamp.microsecond == 0
@@ -358,8 +378,7 @@ def test_from_timestamp_pb_w_nanos():
         seconds = int(delta.total_seconds())
         timestamp = timestamp_pb2.Timestamp(seconds=seconds, nanos=123456789)
 
-        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(
-            timestamp)
+        stamp = datetime_helpers.DatetimeWithNanoseconds.from_timestamp_pb(timestamp)
 
         assert _to_seconds(when) == _to_seconds(stamp)
         assert stamp.microsecond == 123456

From 9dcffee18ed9cf8c61c2992dae81c7e927e43db4 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 11:15:40 +0300
Subject: [PATCH 17/25] update comments

---
 api_core/google/api_core/datetime_helpers.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 9bc6a910974b..d670a12bd3b7 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -116,8 +116,15 @@ def from_iso8601_time(value):
 
 
 def from_rfc3339(value):
+<<<<<<< HEAD
+    """Convert an RFC3339-format timestamp to a native datetime.
+
+    Supported formats include those without fractional seconds, or with
+    any fraction up to nanosecond precision.
+=======
     """Convert a nanosecond-precision or if nanoseconds are missing
     microsecond-precision timestamp to a native datetime.
+>>>>>>> 06bee67b097e485a58415d218f3ac421a04d3d6a
 
     .. note::
         Python datetimes do not support nanosecond precision; this function
@@ -173,6 +180,8 @@ def from_rfc3339_nanos(value):
         ValueError: If the timestamp does not match the RFC3339
             regular expression.
     """
+<<<<<<< HEAD
+=======
     # Raise deprecation warnings for things we want to go away.
     warnings.warn(
         "The `from_rfc3339_nanos` function is deprecated"
@@ -180,6 +189,7 @@ def from_rfc3339_nanos(value):
         DeprecationWarning,
         stacklevel=2,
     )
+>>>>>>> 06bee67b097e485a58415d218f3ac421a04d3d6a
     return from_rfc3339(value)
 
 

From bc18ddbcda37b6a8788c4fbda3bbe118b7b13e96 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 11:25:29 +0300
Subject: [PATCH 18/25] update as requested

---
 api_core/google/api_core/datetime_helpers.py | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index d670a12bd3b7..a7ee91b9365e 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -116,15 +116,10 @@ def from_iso8601_time(value):
 
 
 def from_rfc3339(value):
-<<<<<<< HEAD
     """Convert an RFC3339-format timestamp to a native datetime.
 
     Supported formats include those without fractional seconds, or with
     any fraction up to nanosecond precision.
-=======
-    """Convert a nanosecond-precision or if nanoseconds are missing
-    microsecond-precision timestamp to a native datetime.
->>>>>>> 06bee67b097e485a58415d218f3ac421a04d3d6a
 
     .. note::
         Python datetimes do not support nanosecond precision; this function
@@ -180,16 +175,6 @@ def from_rfc3339_nanos(value):
         ValueError: If the timestamp does not match the RFC3339
             regular expression.
     """
-<<<<<<< HEAD
-=======
-    # Raise deprecation warnings for things we want to go away.
-    warnings.warn(
-        "The `from_rfc3339_nanos` function is deprecated"
-        " use `from_rfc3339` instead.",
-        DeprecationWarning,
-        stacklevel=2,
-    )
->>>>>>> 06bee67b097e485a58415d218f3ac421a04d3d6a
     return from_rfc3339(value)
 
 

From fcd3e6ae34d2b54c38f87fb15c7582fa71bf3b1f Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 11:29:07 +0300
Subject: [PATCH 19/25] black

---
 api_core/google/api_core/bidi.py             | 10 +++++-----
 api_core/google/api_core/iam.py              |  1 +
 api_core/google/api_core/protobuf_helpers.py |  1 +
 api_core/google/api_core/retry.py            |  2 +-
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/api_core/google/api_core/bidi.py b/api_core/google/api_core/bidi.py
index b171a4112a31..be52d97d42f9 100644
--- a/api_core/google/api_core/bidi.py
+++ b/api_core/google/api_core/bidi.py
@@ -172,7 +172,9 @@ def __init__(self, access_limit, time_window):
 
         self._time_window = time_window
         self._access_limit = access_limit
-        self._past_entries = collections.deque(maxlen=access_limit)  # least recent first
+        self._past_entries = collections.deque(
+            maxlen=access_limit
+        )  # least recent first
         self._entry_lock = threading.Lock()
 
     def __enter__(self):
@@ -198,9 +200,7 @@ def __exit__(self, *_):
 
     def __repr__(self):
         return "{}(access_limit={}, time_window={})".format(
-            self.__class__.__name__,
-            self._access_limit,
-            repr(self._time_window),
+            self.__class__.__name__, self._access_limit, repr(self._time_window)
         )
 
 
@@ -423,7 +423,7 @@ def __init__(
 
         if throttle_reopen:
             self._reopen_throttle = _Throttle(
-                access_limit=5, time_window=datetime.timedelta(seconds=10),
+                access_limit=5, time_window=datetime.timedelta(seconds=10)
             )
         else:
             self._reopen_throttle = None
diff --git a/api_core/google/api_core/iam.py b/api_core/google/api_core/iam.py
index 0e108a30679a..df10cf6e7735 100644
--- a/api_core/google/api_core/iam.py
+++ b/api_core/google/api_core/iam.py
@@ -34,6 +34,7 @@
 """
 
 import collections
+
 try:
     from collections import abc as collections_abc
 except ImportError:  # Python 2.7
diff --git a/api_core/google/api_core/protobuf_helpers.py b/api_core/google/api_core/protobuf_helpers.py
index aec6b3620743..92e7844f3e3f 100644
--- a/api_core/google/api_core/protobuf_helpers.py
+++ b/api_core/google/api_core/protobuf_helpers.py
@@ -15,6 +15,7 @@
 """Helpers for :mod:`protobuf`."""
 
 import collections
+
 try:
     from collections import abc as collections_abc
 except ImportError:  # Python 2.7
diff --git a/api_core/google/api_core/retry.py b/api_core/google/api_core/retry.py
index 79343bad3471..5962a68b2a87 100644
--- a/api_core/google/api_core/retry.py
+++ b/api_core/google/api_core/retry.py
@@ -237,7 +237,7 @@ def __init__(
         maximum=_DEFAULT_MAXIMUM_DELAY,
         multiplier=_DEFAULT_DELAY_MULTIPLIER,
         deadline=_DEFAULT_DEADLINE,
-        on_error=None
+        on_error=None,
     ):
         self._predicate = predicate
         self._initial = initial

From ed1ac2f9a37a1f9fe425abad02c21742400d5f41 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 12:05:12 +0300
Subject: [PATCH 20/25] flake8 + test fix

---
 api_core/google/api_core/datetime_helpers.py | 1 -
 api_core/tests/unit/test_datetime_helpers.py | 4 ----
 2 files changed, 5 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index a7ee91b9365e..1f65446a72e3 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -17,7 +17,6 @@
 import calendar
 import datetime
 import re
-import warnings
 
 import pytz
 
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 948723f96ead..a84598112668 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -24,9 +24,6 @@
 
 
 ONE_MINUTE_IN_MICROSECONDS = 60 * 1e6
-MESSAGE = (
-    "The `from_rfc3339_nanos` function is deprecated" " use `from_rfc3339` instead."
-)
 
 
 def test_utcnow():
@@ -137,7 +134,6 @@ def test_from_rfc3339_nanos_is_deprecated():
 
     assert result is from_rfc3339.return_value
     from_rfc3339.assert_called_once_with(value)
-    warn.assert_called_once_with(MESSAGE, DeprecationWarning, stacklevel=2)
 
 
 @pytest.mark.parametrize(

From 3b8f432443fbec06fb407c99f88488b7b3de3b6b Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 12:29:12 +0300
Subject: [PATCH 21/25] remove warning test

---
 api_core/tests/unit/test_datetime_helpers.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index a84598112668..2c53e4dc9b72 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -126,7 +126,6 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
 
 def test_from_rfc3339_nanos_is_deprecated():
     from_rfc3339_patch = mock.patch("google.api_core.datetime_helpers.from_rfc3339")
-    warnings_patch = mock.patch("warnings.warn")
     value = "2009-12-17T12:44:32.123456Z"
 
     with from_rfc3339_patch as from_rfc3339, warnings_patch as warn:

From c7e5b06111e23fc50d92426c0e79087215504cb8 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 12:57:51 +0300
Subject: [PATCH 22/25] test fix

---
 api_core/tests/unit/test_datetime_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 2c53e4dc9b72..49f514b82795 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -128,7 +128,7 @@ def test_from_rfc3339_nanos_is_deprecated():
     from_rfc3339_patch = mock.patch("google.api_core.datetime_helpers.from_rfc3339")
     value = "2009-12-17T12:44:32.123456Z"
 
-    with from_rfc3339_patch as from_rfc3339, warnings_patch as warn:
+    with from_rfc3339_patch as from_rfc3339:
         result = datetime_helpers.from_rfc3339_nanos(value)
 
     assert result is from_rfc3339.return_value

From 0951c9a0a066d799a65c0d6d2c17de45f95f9e75 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Fri, 8 Nov 2019 14:00:31 +0300
Subject: [PATCH 23/25] try flake8 I202 fix

---
 api_core/google/api_core/iam.py              |  2 +-
 api_core/google/api_core/protobuf_helpers.py | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/api_core/google/api_core/iam.py b/api_core/google/api_core/iam.py
index df10cf6e7735..04680eb58869 100644
--- a/api_core/google/api_core/iam.py
+++ b/api_core/google/api_core/iam.py
@@ -34,12 +34,12 @@
 """
 
 import collections
+import warnings
 
 try:
     from collections import abc as collections_abc
 except ImportError:  # Python 2.7
     import collections as collections_abc
-import warnings
 
 # Generic IAM roles
 
diff --git a/api_core/google/api_core/protobuf_helpers.py b/api_core/google/api_core/protobuf_helpers.py
index 92e7844f3e3f..365ef25c6784 100644
--- a/api_core/google/api_core/protobuf_helpers.py
+++ b/api_core/google/api_core/protobuf_helpers.py
@@ -15,11 +15,6 @@
 """Helpers for :mod:`protobuf`."""
 
 import collections
-
-try:
-    from collections import abc as collections_abc
-except ImportError:  # Python 2.7
-    import collections as collections_abc
 import copy
 import inspect
 
@@ -27,6 +22,12 @@
 from google.protobuf import message
 from google.protobuf import wrappers_pb2
 
+try:
+    from collections import abc as collections_abc
+except ImportError:  # Python 2.7
+    import collections as collections_abc
+
+
 _SENTINEL = object()
 _WRAPPER_TYPES = (
     wrappers_pb2.BoolValue,

From 05630fc154d221de2a2a2573062c858f64064934 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Mon, 11 Nov 2019 12:18:43 +0300
Subject: [PATCH 24/25] remove _nanos method + modified tests

---
 api_core/google/api_core/datetime_helpers.py | 23 ++++----------------
 api_core/tests/unit/test_datetime_helpers.py |  8 +++----
 2 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/api_core/google/api_core/datetime_helpers.py b/api_core/google/api_core/datetime_helpers.py
index 1f65446a72e3..e52fb1dd3bcf 100644
--- a/api_core/google/api_core/datetime_helpers.py
+++ b/api_core/google/api_core/datetime_helpers.py
@@ -131,6 +131,9 @@ def from_rfc3339(value):
         datetime.datetime: The datetime object equivalent to the timestamp
         in UTC.
 
+    Raises:
+        ValueError: If the timestamp does not match the RFC3339
+            regular expression.
     """
     with_nanos = _RFC3339_NANOS.match(value)
 
@@ -156,25 +159,7 @@ def from_rfc3339(value):
     return bare_seconds.replace(microsecond=micros, tzinfo=pytz.utc)
 
 
-def from_rfc3339_nanos(value):
-    """DEPRECATED. Convert a nanosecond-precision timestamp to a native datetime.
-
-    .. note::
-        Python datetimes do not support nanosecond precision; this
-        function therefore truncates such values to microseconds.
-
-    Args:
-        value (str): The RFC3339 string to convert.
-
-    Returns:
-        datetime.datetime: The datetime object equivalent to the
-        timestamp in UTC.
-
-    Raises:
-        ValueError: If the timestamp does not match the RFC3339
-            regular expression.
-    """
-    return from_rfc3339(value)
+from_rfc3339_nanos = from_rfc3339  # from_rfc3339_nanos method was deprecated.
 
 
 def to_rfc3339(value, ignore_zone=True):
diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 49f514b82795..7b7544b0c64d 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -125,14 +125,12 @@ def test_from_rfc3339_with_truncated_nanos(truncated, micros):
 
 
 def test_from_rfc3339_nanos_is_deprecated():
-    from_rfc3339_patch = mock.patch("google.api_core.datetime_helpers.from_rfc3339")
     value = "2009-12-17T12:44:32.123456Z"
 
-    with from_rfc3339_patch as from_rfc3339:
-        result = datetime_helpers.from_rfc3339_nanos(value)
+    result = datetime_helpers.from_rfc3339(value)
+    result_nanos = datetime_helpers.from_rfc3339_nanos(value)
 
-    assert result is from_rfc3339.return_value
-    from_rfc3339.assert_called_once_with(value)
+    assert result == result_nanos
 
 
 @pytest.mark.parametrize(

From 97e866276d07349d5f7cd4971843408efcc28168 Mon Sep 17 00:00:00 2001
From: Leonid Emar-Kar <l.emarkar@outlook.com>
Date: Mon, 11 Nov 2019 12:42:51 +0300
Subject: [PATCH 25/25] flake8 update

---
 api_core/tests/unit/test_datetime_helpers.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/api_core/tests/unit/test_datetime_helpers.py b/api_core/tests/unit/test_datetime_helpers.py
index 7b7544b0c64d..4ddcf36103f2 100644
--- a/api_core/tests/unit/test_datetime_helpers.py
+++ b/api_core/tests/unit/test_datetime_helpers.py
@@ -15,7 +15,6 @@
 import calendar
 import datetime
 
-import mock
 import pytest
 import pytz