From c32548c24759f0f4cffa3471030d241ee1eff7bf Mon Sep 17 00:00:00 2001
From: Calvin Ho <18680207+calvh@users.noreply.github.com>
Date: Sat, 21 Aug 2021 17:26:34 -0400
Subject: [PATCH 1/4] TST: Test inequality w/ complex dtypes (GH28050)

Should raise TypeError
---
 pandas/tests/dtypes/test_dtypes.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/pandas/tests/dtypes/test_dtypes.py b/pandas/tests/dtypes/test_dtypes.py
index abb29ce66fd34..4f968dd7200da 100644
--- a/pandas/tests/dtypes/test_dtypes.py
+++ b/pandas/tests/dtypes/test_dtypes.py
@@ -1095,3 +1095,16 @@ def test_period_dtype_compare_to_string():
     dtype = PeriodDtype(freq="M")
     assert (dtype == "period[M]") is True
     assert (dtype != "period[M]") is False
+
+
+def test_compare_complex_dtypes():
+    # GH 28050
+    # https://github.com/pandas-dev/pandas/issues/28050
+    arr = np.arange(5).astype(np.complex128)
+    df = pd.DataFrame(arr)
+
+    with pytest.raises(
+        TypeError,
+        match="'<' not supported between instances of 'complex' and 'complex'",
+    ):
+        df.lt(df.astype(object))

From 807f5470396e5d333aa41d64d08388b783f5bb9d Mon Sep 17 00:00:00 2001
From: Calvin Ho <18680207+calvh@users.noreply.github.com>
Date: Sat, 21 Aug 2021 17:35:46 -0400
Subject: [PATCH 2/4] Add test for complex dtype comparison using '<'

---
 pandas/tests/dtypes/test_dtypes.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pandas/tests/dtypes/test_dtypes.py b/pandas/tests/dtypes/test_dtypes.py
index 4f968dd7200da..37c3584cfa154 100644
--- a/pandas/tests/dtypes/test_dtypes.py
+++ b/pandas/tests/dtypes/test_dtypes.py
@@ -1103,6 +1103,12 @@ def test_compare_complex_dtypes():
     arr = np.arange(5).astype(np.complex128)
     df = pd.DataFrame(arr)
 
+    with pytest.raises(
+        TypeError,
+        match="'<' not supported between instances of 'complex' and 'complex'",
+    ):
+        df < df.astype(object)
+
     with pytest.raises(
         TypeError,
         match="'<' not supported between instances of 'complex' and 'complex'",

From 3b5bf729b3a9659f343eebc9f179587c198a73ff Mon Sep 17 00:00:00 2001
From: Calvin Ho <18680207+calvh@users.noreply.github.com>
Date: Sat, 21 Aug 2021 21:26:00 -0400
Subject: [PATCH 3/4] Refactor code to reduce repetition

Remove https link to issue (keep issue number)
Save match message in variable for multiple use
---
 pandas/tests/dtypes/test_dtypes.py | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/pandas/tests/dtypes/test_dtypes.py b/pandas/tests/dtypes/test_dtypes.py
index 37c3584cfa154..7729f95214bed 100644
--- a/pandas/tests/dtypes/test_dtypes.py
+++ b/pandas/tests/dtypes/test_dtypes.py
@@ -1099,18 +1099,12 @@ def test_period_dtype_compare_to_string():
 
 def test_compare_complex_dtypes():
     # GH 28050
-    # https://github.com/pandas-dev/pandas/issues/28050
     arr = np.arange(5).astype(np.complex128)
     df = pd.DataFrame(arr)
+    msg = "'<' not supported between instances of 'complex' and 'complex'"
 
-    with pytest.raises(
-        TypeError,
-        match="'<' not supported between instances of 'complex' and 'complex'",
-    ):
+    with pytest.raises(TypeError, match=msg):
         df < df.astype(object)
 
-    with pytest.raises(
-        TypeError,
-        match="'<' not supported between instances of 'complex' and 'complex'",
-    ):
+    with pytest.raises(TypeError, match=msg):
         df.lt(df.astype(object))

From ff265c1efa06723beabd623aa1d759ee614564fd Mon Sep 17 00:00:00 2001
From: Calvin Ho <18680207+calvh@users.noreply.github.com>
Date: Sun, 22 Aug 2021 09:50:25 -0400
Subject: [PATCH 4/4] Combine arange call with DataFrame call in test

---
 pandas/tests/dtypes/test_dtypes.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/tests/dtypes/test_dtypes.py b/pandas/tests/dtypes/test_dtypes.py
index 7729f95214bed..30447de874aaa 100644
--- a/pandas/tests/dtypes/test_dtypes.py
+++ b/pandas/tests/dtypes/test_dtypes.py
@@ -1099,8 +1099,7 @@ def test_period_dtype_compare_to_string():
 
 def test_compare_complex_dtypes():
     # GH 28050
-    arr = np.arange(5).astype(np.complex128)
-    df = pd.DataFrame(arr)
+    df = pd.DataFrame(np.arange(5).astype(np.complex128))
     msg = "'<' not supported between instances of 'complex' and 'complex'"
 
     with pytest.raises(TypeError, match=msg):