test: add tests for case sensitive regex in str.contains (#986)

* add test for case sensitive contains

* fix typo in test

tests/expr_and_series/str/contains_test.py

@@ -14,7 +14,9 @@
 df_polars = pl.DataFrame(data)
 
 
-def test_contains(constructor: Constructor, request: pytest.FixtureRequest) -> None:
+def test_contains_case_insensitive(
+    constructor: Constructor, request: pytest.FixtureRequest
+) -> None:
     if "cudf" in str(constructor):
         request.applymarker(pytest.mark.xfail)
 
@@ -29,7 +31,9 @@ def test_contains(constructor: Constructor, request: pytest.FixtureRequest) -> N
     compare_dicts(result, expected)
 
 
-def test_contains_series(constructor_eager: Any, request: pytest.FixtureRequest) -> None:
+def test_contains_series_case_insensitive(
+    constructor_eager: Any, request: pytest.FixtureRequest
+) -> None:
     if "cudf" in str(constructor_eager):
         request.applymarker(pytest.mark.xfail)
 
@@ -42,3 +46,23 @@ def test_contains_series(constructor_eager: Any, request: pytest.FixtureRequest)
         "case_insensitive_match": [False, False, True, True],
     }
     compare_dicts(result, expected)
+
+
+def test_contains_case_sensitive(constructor: Constructor) -> None:
+    df = nw.from_native(constructor(data))
+    result = df.with_columns(nw.col("pets").str.contains("parrot|Dove").alias("result"))
+    expected = {
+        "pets": ["cat", "dog", "rabbit and parrot", "dove"],
+        "result": [False, False, True, False],
+    }
+    compare_dicts(result, expected)
+
+
+def test_contains_series_case_sensitive(constructor_eager: Any) -> None:
+    df = nw.from_native(constructor_eager(data), eager_only=True)
+    result = df.with_columns(case_sensitive_match=df["pets"].str.contains("parrot|Dove"))
+    expected = {
+        "pets": ["cat", "dog", "rabbit and parrot", "dove"],
+        "case_sensitive_match": [False, False, True, False],
+    }
+    compare_dicts(result, expected)