fix: improve mock Forgejo server port handling

.woodpecker/smoke-init.yml

@@ -33,6 +33,6 @@ steps:
     commands:
       - apk add --no-cache bash curl jq git coreutils
       - MOCK_FORGE_PORT=3001 python3 tests/mock-forgejo.py > /tmp/mock.log 2>&1 &
-      # Wait for mock to be ready
-      - for i in $(seq 1 30); do curl -sf http://localhost:3001/api/v1/version >/dev/null 2>&1 && break || sleep 1; done
-      - SMOKE_FORGE_URL=http://localhost:3001 FORGE_URL=http://localhost:3001 bash tests/smoke-init.sh
+      # Wait for mock to be ready (might be on a different port if 3001 is in use)
+      - for i in $(seq 1 30); do curl -sf http://localhost:$MOCK_FORGE_PORT/api/v1/version >/dev/null 2>&1 && break || sleep 1; done
+      - SMOKE_FORGE_URL=http://localhost:$MOCK_FORGE_PORT FORGE_URL=http://localhost:$MOCK_FORGE_PORT bash tests/smoke-init.sh

tests/mock-forgejo.py

@@ -698,11 +698,31 @@ class ThreadingHTTPServer(ThreadingMixIn, HTTPServer):
     allow_reuse_address = True
 
 
+def find_free_port(start_port):
+    """Find a free port starting from start_port."""
+    for port in range(start_port, start_port + 100):
+        try:
+            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            s.bind(("0.0.0.0", port))
+            s.close()
+            return port
+        except OSError:
+            continue
+    return start_port
+
+
 def main():
     """Start the mock server."""
     global SHUTDOWN_REQUESTED
 
-    port = int(os.environ.get("MOCK_FORGE_PORT", 3000))
+    base_port = int(os.environ.get("MOCK_FORGE_PORT", 3000))
+    port = find_free_port(base_port)
+
+    # If we found a different port, update the environment variable
+    if port != base_port:
+        os.environ["MOCK_FORGE_PORT"] = str(port)
+
     server = ThreadingHTTPServer(("0.0.0.0", port), ForgejoHandler)
 
     print(f"Mock Forgejo server starting on port {port}", file=sys.stderr)