GH-30117: [C++][Python] Add "Z" to the end of timestamp print string when tz defined

cpp/src/arrow/pretty_print_test.cc

@@ -350,10 +350,10 @@ TEST_F(TestPrettyPrint, DateTimeTypes) {
     std::vector<int64_t> values = {
         0, 1, 2, 678 + 1000000 * (5 + 60 * (4 + 60 * (3 + 24 * int64_t(1)))), 4};
     static const char* expected = R"expected([
-  1970-01-01 00:00:00.000000,
-  1970-01-01 00:00:00.000001,
+  1970-01-01 00:00:00.000000Z,
+  1970-01-01 00:00:00.000001Z,
   null,
-  1970-01-02 03:04:05.000678,
+  1970-01-02 03:04:05.000678Z,
   null
 ])expected";
     CheckPrimitive<TimestampType, int64_t>(timestamp(TimeUnit::MICRO, "Transylvania"),

cpp/src/arrow/util/formatting.h

@@ -470,7 +470,8 @@ class StringFormatter<TimestampType> {
   using value_type = int64_t;
 
   explicit StringFormatter(const DataType* type)
-      : unit_(checked_cast<const TimestampType&>(*type).unit()) {}
+      : unit_(checked_cast<const TimestampType&>(*type).unit()),
+        timezone_(checked_cast<const TimestampType&>(*type).timezone()) {}
 
   template <typename Duration, typename Appender>
   Return<Appender> operator()(Duration, value_type value, Appender&& append) {
@@ -503,6 +504,9 @@ class StringFormatter<TimestampType> {
     std::array<char, buffer_size> buffer;
     char* cursor = buffer.data() + buffer_size;
 
+    if (timezone_.size() > 0) {
+      detail::FormatOneChar('Z', &cursor);
+    }
     detail::FormatHH_MM_SS(arrow_vendored::date::make_time(since_midnight), &cursor);
     detail::FormatOneChar(' ', &cursor);
     detail::FormatYYYY_MM_DD(timepoint_days, &cursor);
@@ -516,6 +520,7 @@ class StringFormatter<TimestampType> {
 
  private:
   TimeUnit::type unit_;
+  std::string timezone_;
 };
 
 template <typename T>

cpp/src/arrow/util/formatting_util_test.cc

@@ -522,6 +522,34 @@ TEST(Formatting, Timestamp) {
     AssertFormatting(formatter, -2203932304LL * 1000000000LL + 8,
                      "1900-02-28 12:34:56.000000008");
   }
+
+  {
+    auto timestamp_types = {timestamp(TimeUnit::SECOND, "US/Eastern"),
+                            timestamp(TimeUnit::SECOND, "+01:00")};
+    for (auto ty : timestamp_types) {
+      StringFormatter<TimestampType> formatter(ty.get());
+
+      AssertFormatting(formatter, 0, "1970-01-01 00:00:00Z");
+    }
+  }
+
+  {
+    auto ty = timestamp(TimeUnit::MILLI, "Pacific/Maruesas");
+    StringFormatter<TimestampType> formatter(ty.get());
+    AssertFormatting(formatter, 0, "1970-01-01 00:00:00.000Z");
+  }
+
+  {
+    auto ty = timestamp(TimeUnit::MICRO, "-42:00");
+    StringFormatter<TimestampType> formatter(ty.get());
+    AssertFormatting(formatter, 0, "1970-01-01 00:00:00.000000Z");
+  }
+
+  {
+    auto ty = timestamp(TimeUnit::NANO, "Mars/Mariner_Valley");
+    StringFormatter<TimestampType> formatter(ty.get());
+    AssertFormatting(formatter, 0, "1970-01-01 00:00:00.000000000Z");
+  }
 }
 
 TEST(Formatting, Interval) {

python/pyarrow/tests/test_types.py

@@ -487,6 +487,17 @@ def test_timestamp():
             pa.timestamp(invalid_unit)
 
 
+def test_timestamp_print():
+    for unit in ('s', 'ms', 'us', 'ns'):
+        for tz in ('UTC', 'Europe/Paris', 'Pacific/Marquesas',
+                   'Mars/Mariner_Valley', '-00:42', '+42:00'):
+            ty = pa.timestamp(unit, tz=tz)
+            arr = pa.array([0], ty)
+            assert "Z" in str(arr)
+        arr = pa.array([0], pa.timestamp(unit))
+        assert "Z" not in str(arr)
+
+
 def test_time32_units():
     for valid_unit in ('s', 'ms'):
         ty = pa.time32(valid_unit)