test: reproduce #973

Github-Issue: #973

Author: felixweinberger

tests/issues/test_973_url_decoding.py

@@ -0,0 +1,80 @@
+"""Test that URL-encoded parameters are decoded in resource templates.
+
+Regression test for https://github.com/modelcontextprotocol/python-sdk/issues/973
+"""
+
+from mcp.server.fastmcp.resources import ResourceTemplate
+
+
+class TestUrlParameterDecoding:
+    """Test URL parameter decoding in resource templates."""
+
+    def test_template_matches_decodes_space(self):
+        """Test that %20 is decoded to space."""
+
+        def search(query: str) -> str:  # pragma: no cover
+            return f"Results for: {query}"
+
+        template = ResourceTemplate.from_function(
+            fn=search,
+            uri_template="search://{query}",
+            name="search",
+        )
+
+        params = template.matches("search://hello%20world")
+        assert params is not None
+        assert params["query"] == "hello world"
+
+    def test_template_matches_decodes_accented_characters(self):
+        """Test that %C3%A9 is decoded to e with accent."""
+
+        def search(query: str) -> str:  # pragma: no cover
+            return f"Results for: {query}"
+
+        template = ResourceTemplate.from_function(
+            fn=search,
+            uri_template="search://{query}",
+            name="search",
+        )
+
+        params = template.matches("search://caf%C3%A9")
+        assert params is not None
+        assert params["query"] == "cafe"  # encoded as UTF-8
+
+    def test_template_matches_decodes_complex_phrase(self):
+        """Test complex French phrase from the original issue."""
+
+        def search(query: str) -> str:  # pragma: no cover
+            return f"Results for: {query}"
+
+        template = ResourceTemplate.from_function(
+            fn=search,
+            uri_template="search://{query}",
+            name="search",
+        )
+
+        params = template.matches(
+            "search://stick%20correcteur%20teint%C3%A9%20anti-imperfections"
+        )
+        assert params is not None
+        assert params["query"] == "stick correcteur teinte anti-imperfections"
+
+    def test_template_matches_preserves_plus_sign(self):
+        """Test that plus sign remains as plus (not converted to space).
+
+        In URI encoding, %20 is space. Plus-as-space is only for
+        application/x-www-form-urlencoded (HTML forms).
+        """
+
+        def search(query: str) -> str:  # pragma: no cover
+            return f"Results for: {query}"
+
+        template = ResourceTemplate.from_function(
+            fn=search,
+            uri_template="search://{query}",
+            name="search",
+        )
+
+        params = template.matches("search://hello+world")
+        assert params is not None
+        assert params["query"] == "hello+world"