fix more tests

Author: jorisvandenbossche

pandas/core/indexes/base.py

@@ -6397,6 +6397,18 @@ def _find_common_type_compat(self, target) -> DtypeObj:
             if len(self) == 0 and (
                 isinstance(self, RangeIndex) or self.dtype == np.object_
             ):
+                if target_dtype.kind == "M":
+                    if hasattr(target_dtype, "tz"):
+                        target_dtype_ns = DatetimeTZDtype("ns", tz=target_dtype.tz)
+                    else:
+                        target_dtype_ns = np.dtype("datetime64[ns]")
+                    try:
+                        Index(target, dtype=target_dtype_ns, copy=False)
+                    except OutOfBoundsDatetime:
+                        return np.dtype(object)
+                    except Exception:
+                        pass
+                    return target_dtype_ns
                 return target_dtype
             if (
                 isinstance(target, Index)

pandas/tests/frame/indexing/test_coercion.py

@@ -113,7 +113,7 @@ def test_26395(indexer_al):
     expected = DataFrame(
         {"D": [0, 0, 44.5]},
         index=["A", "B", "C"],
-        columns=pd.Index(["D"], dtype=object),
+        columns=["D"],
         dtype=np.float64,
     )
     tm.assert_frame_equal(df, expected)
@@ -125,7 +125,7 @@ def test_26395(indexer_al):
     expected = DataFrame(
         {"D": [0, 0, "hello"]},
         index=["A", "B", "C"],
-        columns=pd.Index(["D"], dtype=object),
+        columns=["D"],
         dtype=object,
     )
     tm.assert_frame_equal(df, expected)

pandas/tests/indexes/test_setops.py

@@ -64,7 +64,7 @@ def test_union_same_types(index):
     assert idx1.union(idx2).dtype == idx1.dtype
 
 
-def test_union_different_types(index_flat, index_flat2, request):
+def test_union_different_types(index_flat, index_flat2, request, using_infer_string):
     # This test only considers combinations of indices
     # GH 23525
     idx1 = index_flat
@@ -93,6 +93,13 @@ def test_union_different_types(index_flat, index_flat2, request):
         request.applymarker(mark)
 
     common_dtype = find_common_type([idx1.dtype, idx2.dtype])
+    if using_infer_string:
+        if len(idx1) == 0 and (idx1.dtype.kind == "O" or isinstance(idx1, RangeIndex)):
+            common_dtype = idx2.dtype
+        elif len(idx2) == 0 and (
+            idx2.dtype.kind == "O" or isinstance(idx2, RangeIndex)
+        ):
+            common_dtype = idx1.dtype
 
     warn = None
     msg = "'<' not supported between"

pandas/tests/resample/test_base.py

@@ -9,7 +9,6 @@
 from pandas import (
     DataFrame,
     DatetimeIndex,
-    Index,
     MultiIndex,
     NaT,
     PeriodIndex,
@@ -293,7 +292,7 @@ def test_resample_count_empty_dataframe(freq, empty_frame_dti):
 
     index = _asfreq_compat(empty_frame_dti.index, freq)
 
-    expected = DataFrame(dtype="int64", index=index, columns=Index(["a"], dtype=object))
+    expected = DataFrame(dtype="int64", index=index, columns=["a"])
 
     tm.assert_frame_equal(result, expected)