Add test coverage for scrapy.utils.decorators (#7645)

tests/test_utils_decorators.py

@@ -0,0 +1,107 @@
+from __future__ import annotations
+
+import warnings
+
+import pytest
+from twisted.internet.defer import Deferred
+
+from scrapy.exceptions import ScrapyDeprecationWarning
+from scrapy.utils.decorators import _warn_spider_arg, deprecated, inthread
+from scrapy.utils.defer import maybe_deferred_to_future
+from tests.utils.decorators import coroutine_test
+
+
+class TestDeprecated:
+    def test_warns_and_still_calls(self):
+        @deprecated()
+        def add(a, b):
+            return a + b
+
+        with pytest.warns(
+            ScrapyDeprecationWarning, match=r"Call to deprecated function add\."
+        ):
+            result = add(2, 3)
+
+        assert result == 5
+
+    def test_use_instead_in_message(self):
+        @deprecated(use_instead="other_function")
+        def old():
+            return None
+
+        with pytest.warns(
+            ScrapyDeprecationWarning,
+            match=r"Call to deprecated function old\. Use other_function instead\.",
+        ):
+            old()
+
+    def test_applied_without_parentheses(self):
+        @deprecated
+        def square(x):
+            return x * x
+
+        with pytest.warns(
+            ScrapyDeprecationWarning, match=r"Call to deprecated function square\."
+        ) as record:
+            result = square(4)
+
+        assert result == 16
+        # No "Use ... instead." part when applied directly to the function.
+        assert "instead" not in str(record[0].message)
+
+
+class TestInthread:
+    @coroutine_test
+    async def test_returns_deferred_with_result(self):
+        @inthread
+        def multiply(a, b):
+            return a * b
+
+        deferred = multiply(6, 7)
+        assert isinstance(deferred, Deferred)
+        assert await maybe_deferred_to_future(deferred) == 42
+
+
+class TestWarnSpiderArg:
+    def test_sync_warns_with_spider_arg(self):
+        @_warn_spider_arg
+        def parse(response, spider=None):
+            return response
+
+        with pytest.warns(
+            ScrapyDeprecationWarning, match=r"Passing a 'spider' argument"
+        ):
+            assert parse("response", spider="spider") == "response"
+
+    def test_sync_no_warning_without_spider_arg(self):
+        @_warn_spider_arg
+        def parse(response, spider=None):
+            return response
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", category=ScrapyDeprecationWarning)
+            assert parse("response") == "response"
+
+    @coroutine_test
+    async def test_async_warns_with_spider_arg(self):
+        @_warn_spider_arg
+        async def parse(response, spider=None):
+            return response
+
+        with pytest.warns(
+            ScrapyDeprecationWarning, match=r"Passing a 'spider' argument"
+        ):
+            assert await parse("response", spider="spider") == "response"
+
+    @coroutine_test
+    async def test_asyncgen_warns_with_spider_arg(self):
+        @_warn_spider_arg
+        async def parse(response, spider=None):
+            yield response
+
+        with pytest.warns(
+            ScrapyDeprecationWarning, match=r"Passing a 'spider' argument"
+        ):
+            results = [item async for item in parse("response", spider="spider")]
+
+        assert results == ["response"]