Add tests

Author: xinrong-meng

databricks/koalas/tests/indexes/test_datetime.py

@@ -128,3 +128,32 @@ def test_strftime(self):
             self.assert_eq(
                 kidx.strftime(date_format="%B %d, %Y"), pidx.strftime(date_format="%B %d, %Y")
             )
+
+    def test_arithmetic_op_exceptions(self):
+        for kidx, pidx in self.idx_pairs:
+            py_datetime = pidx.to_pydatetime()
+            for other in [1, 0.1, kidx, kidx.to_series().reset_index(drop=True), py_datetime]:
+                expected_err_msg = "addition can not be applied to date times."
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx + other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other + kidx)
+
+                expected_err_msg = "multiplication can not be applied to date times."
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx * other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other * kidx)
+
+                expected_err_msg = "division can not be applied to date times."
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx / other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other / kidx)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx // other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other // kidx)
+
+                expected_err_msg = "modulo can not be applied to date times."
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx % other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other % kidx)
+
+            for other in [1, 0.1, py_datetime]:
+                expected_err_msg = "datetime subtraction can only be applied to datetime series."
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kidx - other)
+                self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other - kidx)
+
+            self.assertRaises(NotImplementedError, lambda: py_datetime - kidx)

databricks/koalas/tests/test_series_datetime.py

@@ -75,6 +75,37 @@ def test_timestamp_subtraction(self):
         with self.assertRaisesRegex(TypeError, expected_error_message):
             1 - kdf["a"]
 
+    def test_arithmetic_op_exceptions(self):
+        kser = self.ks_start_date
+        py_datetime = self.pd_start_date.dt.to_pydatetime()
+        datetime_index = ks.Index(self.pd_start_date)
+
+        for other in [1, 0.1, kser, datetime_index, py_datetime]:
+            expected_err_msg = "addition can not be applied to date times."
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser + other)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other + kser)
+
+            expected_err_msg = "multiplication can not be applied to date times."
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser * other)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other * kser)
+
+            expected_err_msg = "division can not be applied to date times."
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser / other)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other / kser)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser // other)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other // kser)
+
+            expected_err_msg = "modulo can not be applied to date times."
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser % other)
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: other % kser)
+
+        ks.set_option("compute.ops_on_diff_frames", True)
+        for other in [1, 0.1, py_datetime]:
+            expected_err_msg = "datetime subtraction can only be applied to datetime series."
+            self.assertRaisesRegex(TypeError, expected_err_msg, lambda: kser - other)
+
+        self.assertRaises(NotImplementedError, lambda: py_datetime - kser)
+
     def test_date_subtraction(self):
         pdf = self.pdf1
         kdf = ks.from_pandas(pdf)