From f0a449e72535172b958a2099b00fab70f041c6df Mon Sep 17 00:00:00 2001
From: gfyoung <gfyoung17+GitHub@gmail.com>
Date: Tue, 29 Oct 2019 04:46:15 +0000
Subject: [PATCH 1/2] TST: Test named aggregations with functions

Closes https://github.com/pandas-dev/pandas/issues/28467
---
 .../tests/groupby/aggregate/test_aggregate.py | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/pandas/tests/groupby/aggregate/test_aggregate.py b/pandas/tests/groupby/aggregate/test_aggregate.py
index aa80c461a00e7..f9a4acb12499f 100644
--- a/pandas/tests/groupby/aggregate/test_aggregate.py
+++ b/pandas/tests/groupby/aggregate/test_aggregate.py
@@ -494,6 +494,52 @@ def test_mangled(self):
         )
         tm.assert_frame_equal(result, expected)
 
+    def test_lambda_named_agg(self):
+        # see gh-28467
+        animals = DataFrame(
+            {
+                "kind": ["cat", "dog", "cat", "dog"],
+                "height": [9.1, 6.0, 9.5, 34.0],
+                "weight": [7.9, 7.5, 9.9, 198.0],
+            }
+        )
+
+        result = animals.groupby("kind").agg(
+            mean_height=("height", "mean"),
+            perc90=("height", lambda s: np.percentile(s, q=0.90)),
+        )
+        expected = DataFrame(
+            [[9.3, 9.1036], [20.0, 6.252]],
+            columns=["mean_height", "perc90"],
+            index=Index(["cat", "dog"], name="kind"),
+        )
+
+        tm.assert_frame_equal(result, expected)
+
+    def test_func_named_agg(self):
+        # see gh-28467
+        def myfunc(s):
+            return np.percentile(s, q=0.90)
+
+        animals = DataFrame(
+            {
+                "kind": ["cat", "dog", "cat", "dog"],
+                "height": [9.1, 6.0, 9.5, 34.0],
+                "weight": [7.9, 7.5, 9.9, 198.0],
+            }
+        )
+
+        result = animals.groupby("kind").agg(
+            mean_height=("height", "mean"), perc90=("height", myfunc)
+        )
+        expected = DataFrame(
+            [[9.3, 9.1036], [20.0, 6.252]],
+            columns=["mean_height", "perc90"],
+            index=Index(["cat", "dog"], name="kind"),
+        )
+
+        tm.assert_frame_equal(result, expected)
+
 
 class TestLambdaMangling:
     def test_maybe_mangle_lambdas_passthrough(self):

From f11fcb16f04a9e3fc0f2423f6c527e200e50bccf Mon Sep 17 00:00:00 2001
From: gfyoung <gfyoung17+GitHub@gmail.com>
Date: Tue, 29 Oct 2019 06:55:11 +0000
Subject: [PATCH 2/2] MAINT: Use pytest idiom for added tests

---
 .../tests/groupby/aggregate/test_aggregate.py | 61 +++++++------------
 1 file changed, 21 insertions(+), 40 deletions(-)

diff --git a/pandas/tests/groupby/aggregate/test_aggregate.py b/pandas/tests/groupby/aggregate/test_aggregate.py
index f9a4acb12499f..b56da5fba6f80 100644
--- a/pandas/tests/groupby/aggregate/test_aggregate.py
+++ b/pandas/tests/groupby/aggregate/test_aggregate.py
@@ -494,51 +494,32 @@ def test_mangled(self):
         )
         tm.assert_frame_equal(result, expected)
 
-    def test_lambda_named_agg(self):
-        # see gh-28467
-        animals = DataFrame(
-            {
-                "kind": ["cat", "dog", "cat", "dog"],
-                "height": [9.1, 6.0, 9.5, 34.0],
-                "weight": [7.9, 7.5, 9.9, 198.0],
-            }
-        )
 
-        result = animals.groupby("kind").agg(
-            mean_height=("height", "mean"),
-            perc90=("height", lambda s: np.percentile(s, q=0.90)),
-        )
-        expected = DataFrame(
-            [[9.3, 9.1036], [20.0, 6.252]],
-            columns=["mean_height", "perc90"],
-            index=Index(["cat", "dog"], name="kind"),
-        )
-
-        tm.assert_frame_equal(result, expected)
+def myfunc(s):
+    return np.percentile(s, q=0.90)
 
-    def test_func_named_agg(self):
-        # see gh-28467
-        def myfunc(s):
-            return np.percentile(s, q=0.90)
 
-        animals = DataFrame(
-            {
-                "kind": ["cat", "dog", "cat", "dog"],
-                "height": [9.1, 6.0, 9.5, 34.0],
-                "weight": [7.9, 7.5, 9.9, 198.0],
-            }
-        )
+@pytest.mark.parametrize("func", [lambda s: np.percentile(s, q=0.90), myfunc])
+def test_lambda_named_agg(func):
+    # see gh-28467
+    animals = DataFrame(
+        {
+            "kind": ["cat", "dog", "cat", "dog"],
+            "height": [9.1, 6.0, 9.5, 34.0],
+            "weight": [7.9, 7.5, 9.9, 198.0],
+        }
+    )
 
-        result = animals.groupby("kind").agg(
-            mean_height=("height", "mean"), perc90=("height", myfunc)
-        )
-        expected = DataFrame(
-            [[9.3, 9.1036], [20.0, 6.252]],
-            columns=["mean_height", "perc90"],
-            index=Index(["cat", "dog"], name="kind"),
-        )
+    result = animals.groupby("kind").agg(
+        mean_height=("height", "mean"), perc90=("height", func)
+    )
+    expected = DataFrame(
+        [[9.3, 9.1036], [20.0, 6.252]],
+        columns=["mean_height", "perc90"],
+        index=Index(["cat", "dog"], name="kind"),
+    )
 
-        tm.assert_frame_equal(result, expected)
+    tm.assert_frame_equal(result, expected)
 
 
 class TestLambdaMangling: