adjust repr tests to account for different platforms (pydata#9127)

Adjust the expectations in repr tests to account for different object
sizes and numpy type representations across platforms, particularly
fixing the tests on 32-bit platforms.

Firstly, this involves getting the object type size from NumPy and using
it to adjust the expectations in DataArray and Dataset tests.  The tests
were already using int64 type consistently, so only the sizes used
for Python objects needed to be adjusted.

Secondly, this involves fixing `test_array_repr_dtypes_unix`.  The test
specifically focuses on testing a 32-bit, 64-bit and "native" data type,
which affect both size and actual representation (NumPy skips the dtype
attribute for the native data type).  Get the expected size from NumPy
for the native int type, and reuse `repr()` from NumPy for all array
types.

xarray/tests/test_dataarray.py

@@ -110,13 +110,14 @@ def test_repr(self) -> None:
         assert expected == repr(data_array)
 
     def test_repr_multiindex(self) -> None:
+        obj_size = np.dtype("O").itemsize
         expected = dedent(
-            """\
+            f"""\
             <xarray.DataArray (x: 4)> Size: 32B
             array([0, 1, 2, 3], dtype=uint64)
             Coordinates:
-              * x        (x) object 32B MultiIndex
-              * level_1  (x) object 32B 'a' 'a' 'b' 'b'
+              * x        (x) object {4 * obj_size}B MultiIndex
+              * level_1  (x) object {4 * obj_size}B 'a' 'a' 'b' 'b'
               * level_2  (x) int64 32B 1 2 1 2"""
         )
         assert expected == repr(self.mda)
@@ -129,15 +130,16 @@ def test_repr_multiindex_long(self) -> None:
         mda_long = DataArray(
             list(range(32)), coords={"x": mindex_long}, dims="x"
         ).astype(np.uint64)
+        obj_size = np.dtype("O").itemsize
         expected = dedent(
-            """\
+            f"""\
             <xarray.DataArray (x: 32)> Size: 256B
             array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16,
                    17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31],
                   dtype=uint64)
             Coordinates:
-              * x        (x) object 256B MultiIndex
-              * level_1  (x) object 256B 'a' 'a' 'a' 'a' 'a' 'a' ... 'd' 'd' 'd' 'd' 'd' 'd'
+              * x        (x) object {32 * obj_size}B MultiIndex
+              * level_1  (x) object {32 * obj_size}B 'a' 'a' 'a' 'a' 'a' 'a' ... 'd' 'd' 'd' 'd' 'd' 'd'
               * level_2  (x) int64 256B 1 2 3 4 5 6 7 8 1 2 3 4 ... 5 6 7 8 1 2 3 4 5 6 7 8"""
         )
         assert expected == repr(mda_long)

xarray/tests/test_dataset.py

@@ -335,13 +335,14 @@ def test_repr(self) -> None:
 
     def test_repr_multiindex(self) -> None:
         data = create_test_multiindex()
+        obj_size = np.dtype("O").itemsize
         expected = dedent(
-            """\
-            <xarray.Dataset> Size: 96B
+            f"""\
+            <xarray.Dataset> Size: {8 * obj_size + 32}B
             Dimensions:  (x: 4)
             Coordinates:
-              * x        (x) object 32B MultiIndex
-              * level_1  (x) object 32B 'a' 'a' 'b' 'b'
+              * x        (x) object {4 * obj_size}B MultiIndex
+              * level_1  (x) object {4 * obj_size}B 'a' 'a' 'b' 'b'
               * level_2  (x) int64 32B 1 2 1 2
             Data variables:
                 *empty*"""
@@ -357,12 +358,12 @@ def test_repr_multiindex(self) -> None:
         midx_coords = Coordinates.from_pandas_multiindex(midx, "x")
         data = Dataset({}, midx_coords)
         expected = dedent(
-            """\
-            <xarray.Dataset> Size: 96B
+            f"""\
+            <xarray.Dataset> Size: {8 * obj_size + 32}B
             Dimensions:                  (x: 4)
             Coordinates:
-              * x                        (x) object 32B MultiIndex
-              * a_quite_long_level_name  (x) object 32B 'a' 'a' 'b' 'b'
+              * x                        (x) object {4 * obj_size}B MultiIndex
+              * a_quite_long_level_name  (x) object {4 * obj_size}B 'a' 'a' 'b' 'b'
               * level_2                  (x) int64 32B 1 2 1 2
             Data variables:
                 *empty*"""

xarray/tests/test_formatting.py

@@ -1080,29 +1080,32 @@ def test_array_repr_dtypes_unix() -> None:
 
     # Signed integer dtypes
 
-    ds = xr.DataArray(np.array([0]), dims="x")
+    array = np.array([0])
+    ds = xr.DataArray(array, dims="x")
     actual = repr(ds)
-    expected = """
-<xarray.DataArray (x: 1)> Size: 8B
-array([0])
+    expected = f"""
+<xarray.DataArray (x: 1)> Size: {array.dtype.itemsize}B
+{repr(array)}
 Dimensions without coordinates: x
         """.strip()
     assert actual == expected
 
-    ds = xr.DataArray(np.array([0], dtype="int32"), dims="x")
+    array = np.array([0], dtype="int32")
+    ds = xr.DataArray(array, dims="x")
     actual = repr(ds)
-    expected = """
+    expected = f"""
 <xarray.DataArray (x: 1)> Size: 4B
-array([0], dtype=int32)
+{repr(array)}
 Dimensions without coordinates: x
         """.strip()
     assert actual == expected
 
-    ds = xr.DataArray(np.array([0], dtype="int64"), dims="x")
+    array = np.array([0], dtype="int64")
+    ds = xr.DataArray(array, dims="x")
     actual = repr(ds)
-    expected = """
+    expected = f"""
 <xarray.DataArray (x: 1)> Size: 8B
-array([0])
+{repr(array)}
 Dimensions without coordinates: x
         """.strip()
     assert actual == expected