Added unit tests for ExpectColumnTypeToBe expectation in tests/expectations/core/test_expect_column_type_to_be.py

Author: Mansib Rahman

tests/expectations/core/test_expect_column_type_to_be.py

@@ -0,0 +1,52 @@
+import numpy as np
+
+import great_expectations.expectations as gxe
+from great_expectations.expectations.expectation_configuration import (
+    ExpectationConfiguration,
+)
+
+
+def test_expectation_is_registered_and_constructible():
+    expectation = gxe.ExpectColumnTypeToBe(column="col", type_="int64")
+    assert expectation.column == "col"
+    assert expectation.type_ == "int64"
+
+
+def test_validate_pandas_success():
+    expectation = gxe.ExpectColumnTypeToBe(column="col", type_="int64")
+    result = expectation._validate_pandas(
+        actual_column_type=np.dtype("int64"), expected_type="int64"
+    )
+    assert result == {"success": True, "result": {"observed_value": "int64"}}
+
+
+def test_validate_pandas_failure_returns_schema_level_result():
+    expectation = gxe.ExpectColumnTypeToBe(column="col", type_="int64")
+    result = expectation._validate_pandas(
+        actual_column_type=np.dtype("object"), expected_type="int64"
+    )
+    # Schema-level result shape (observed_value only) is preserved on failure,
+    # with no row-level fields.
+    assert result == {"success": False, "result": {"observed_value": "object_"}}
+
+
+def test_validate_pandas_object_column_is_schema_level():
+    # The core behavior: a pandas 'object' column reports its declared dtype and
+    # is not checked row-by-row (unlike ExpectColumnValuesToBeOfType).
+    expectation = gxe.ExpectColumnTypeToBe(column="col", type_="object")
+    result = expectation._validate_pandas(
+        actual_column_type=np.dtype("object"), expected_type="object"
+    )
+    assert result == {"success": True, "result": {"observed_value": "object_"}}
+
+
+def test_prescriptive_renderer_template():
+    configuration = ExpectationConfiguration(
+        type="expect_column_type_to_be",
+        kwargs={"column": "col", "type_": "int64"},
+    )
+    rendered = gxe.ExpectColumnTypeToBe._prescriptive_renderer(configuration=configuration)
+    string_template = rendered[0].string_template
+    assert string_template["template"] == "$column type must be $type_."
+    assert string_template["params"]["column"] == "col"
+    assert string_template["params"]["type_"] == "int64"