SONARPY-3876 S1172 Fixing FPs on Django middleware conventional function parameters (#944)

GitOrigin-RevId: 47e0aba447a9b6095c644691b76dee20c18e39cb

Author: joke1196

python-checks/src/main/java/org/sonar/python/checks/UnusedFunctionParameterCheck.java

@@ -41,6 +41,8 @@
 import org.sonar.plugins.python.api.tree.Token;
 import org.sonar.plugins.python.api.tree.Tree;
 import org.sonar.plugins.python.api.tree.Tree.Kind;
+import org.sonar.plugins.python.api.types.v2.matchers.TypeMatcher;
+import org.sonar.plugins.python.api.types.v2.matchers.TypeMatchers;
 import org.sonar.plugins.python.api.tree.Trivia;
 import org.sonar.python.checks.utils.CheckUtils;
 import org.sonar.python.checks.utils.StringLiteralValuesCollector;
@@ -57,6 +59,12 @@ public class UnusedFunctionParameterCheck extends PythonSubscriptionCheck {
 
   private static final Set<String> AWS_LAMBDA_PARAMETERS = Set.of("event", "context");
 
+  private static final Set<String> DJANGO_MIDDLEWARE_METHODS = Set.of(
+    "process_request", "process_exception", "process_view", "process_template_response");
+
+  private static final TypeMatcher MIDDLEWARE_MIXIN_MATCHER = TypeMatchers.isFunctionOwnerSatisfying(
+    TypeMatchers.isOrExtendsType("django.utils.deprecation.MiddlewareMixin"));
+
   @Override
   public void initialize(Context context) {
     context.registerSyntaxNodeConsumer(Kind.FUNCDEF, ctx -> checkFunctionParameter(ctx, ((FunctionDef) ctx.syntaxNode())));
@@ -119,6 +127,7 @@ private static boolean isException(SubscriptionContext ctx, FunctionDef function
       hasNonCallUsages(functionSymbol) ||
       isTestFunction(ctx, functionDef) ||
       isDjangoView(functionDef) ||
+      isDjangoMiddlewareFunction(ctx, functionDef) ||
       isAbstractClass(functionDef);
   }
 
@@ -201,4 +210,13 @@ private static boolean isDjangoView(FunctionDef functionDef) {
     FunctionSymbolImpl functionSymbolImpl = (FunctionSymbolImpl) functionSymbol;
     return functionSymbolImpl != null && functionSymbolImpl.isDjangoView();
   }
+
+
+  private static boolean isDjangoMiddlewareFunction(SubscriptionContext ctx, FunctionDef functionDef) {
+    String functionName = functionDef.name().name();
+    if (!DJANGO_MIDDLEWARE_METHODS.contains(functionName)) {
+      return false;
+    }
+    return MIDDLEWARE_MIXIN_MATCHER.isTrueFor(functionDef.name(), ctx);
+  }
 }

python-checks/src/test/java/org/sonar/python/checks/UnusedFunctionParameterCheckTest.java

@@ -57,4 +57,11 @@ void test_django() {
       ),
       new UnusedFunctionParameterCheck());
   }
+
+  @Test
+  void test_django_middleware() {
+    PythonCheckVerifier.verify(
+      "src/test/resources/checks/unusedFunctionParameter/django/middleware.py",
+      new UnusedFunctionParameterCheck());
+  }
 }

python-checks/src/test/resources/checks/unusedFunctionParameter/django/middleware.py

@@ -0,0 +1,32 @@
+from django.utils.deprecation import MiddlewareMixin
+
+
+class MyMiddleware(MiddlewareMixin):
+    def process_request(self, request):  # Compliant - Django middleware hook
+        print("logging")
+
+    def process_exception(
+        self, request, exception
+    ):  # Compliant - Django middleware hook
+        print("logging")
+
+    def process_view(
+        self, request, view_func, view_args, view_kwargs
+    ):  # Compliant - Django middleware hook
+        print("logging")
+
+    def process_template_response(
+        self, request, response
+    ):  # Compliant - Django middleware hook
+        print("logging")
+
+    def some_other_method(self, foo):  # Noncompliant
+        print("logging")
+
+
+class NotAMiddleware:
+    def process_request(self, request):  # Noncompliant
+        print("logging")
+
+    def process_exception(self, request, exception):  # Noncompliant 2
+        print("logging")