Refactor test_combine_first dataframe (#63295)

Author: Tsmith-77

pandas/tests/frame/methods/test_combine_first.py

@@ -30,17 +30,19 @@ def test_combine_first_mixed(self):
 combined=f.combine_first(g)
 tm.assert_frame_equal(combined, exp)
 
-deftest_combine_first(self, float_frame):
-# disjoint
+deftest_combine_first_disjoint(self, float_frame):
 head, tail=float_frame[:5], float_frame[5:]
-
 combined=head.combine_first(tail)
 reordered_frame=float_frame.reindex(combined.index)
+
 tm.assert_frame_equal(combined, reordered_frame)
 tm.assert_index_equal(combined.columns, float_frame.columns)
 tm.assert_series_equal(combined["A"], reordered_frame["A"])
 
-# same index
+tm.assert_series_equal(combined["A"].reindex(head.index), head["A"])
+tm.assert_series_equal(combined["A"].reindex(tail.index), tail["A"])
+
+deftest_combine_first_same_index(self, float_frame):
 fcopy=float_frame.copy()
 fcopy["A"] =1
 delfcopy["C"]
@@ -56,36 +58,36 @@ def test_combine_first(self, float_frame):
 tm.assert_series_equal(combined["C"], fcopy2["C"])
 tm.assert_series_equal(combined["D"], fcopy["D"])
 
-# overlap
-head, tail=reordered_frame[:10].copy(), reordered_frame
+deftest_combine_first_overlap(self, float_frame):
+combined=float_frame[:5].combine_first(float_frame[5:])
+reordered_frame=float_frame.reindex(combined.index)
+head, tail=reordered_frame[:10].copy(), reordered_frame.copy()
 head["A"] =1
-
 combined=head.combine_first(tail)
 assert (combined["A"][:10] ==1).all()
 
-# reverse overlap
+deftest_combine_first_reverse_overlap(self, float_frame):
+combined=float_frame[:5].combine_first(float_frame[5:])
+reordered_frame=float_frame.reindex(combined.index)
+head, tail=reordered_frame[:10].copy(), reordered_frame
+
 tail.iloc[:10, tail.columns.get_loc("A")] =0
 combined=tail.combine_first(head)
 assert (combined["A"][:10] ==0).all()
 
-# no overlap
-f=float_frame[:10]
-g=float_frame[10:]
-combined=f.combine_first(g)
-tm.assert_series_equal(combined["A"].reindex(f.index), f["A"])
-tm.assert_series_equal(combined["A"].reindex(g.index), g["A"])
-
-# corner cases
+deftest_combine_first_with_empty(self, float_frame):
 comb=float_frame.combine_first(DataFrame())
 tm.assert_frame_equal(comb, float_frame)
 
 comb=DataFrame().combine_first(float_frame)
 tm.assert_frame_equal(comb, float_frame.sort_index())
 
+deftest_combine_first_with_new_index(self, float_frame):
 comb=float_frame.combine_first(DataFrame(index=["faz", "boo"]))
 assert"faz"incomb.index
 
-# #2525
+deftest_combine_first_column_union(self):
+# GH#2525
 df=DataFrame({"a": [1]}, index=[datetime(2012, 1, 1)])
 df2=DataFrame(columns=["b"])
 result=df.combine_first(df2)