Reach 100% line coverage without duplicating test suites

bunfig.toml

@@ -1,4 +1,16 @@
 [test]
 preload = ["./packages/wouter/test/setup.ts"]
 coverageSkipTestFiles = true
-coveragePathIgnorePatterns = ["**/test/**"]
+coveragePathIgnorePatterns = [
+  "**/test/**",
+  # temporary copies of packages/wouter/src/* created by preact.test.tsx;
+  # already measured at their original path (react-deps.js is preact-specific and stays measured)
+  "packages/wouter-preact/src/index.js",
+  "packages/wouter-preact/src/paths.js",
+  "packages/wouter-preact/src/memory-location.js",
+  "packages/wouter-preact/src/use-browser-location.js",
+  "packages/wouter-preact/src/use-hash-location.js",
+  "packages/wouter-preact/src/use-sync-external-store.js",
+  "packages/wouter-preact/src/use-sync-external-store.native.js",
+]
+coverageThreshold = { lines = 0.99 }

packages/wouter-preact/test/preact.test.tsx

@@ -157,6 +157,56 @@ describe("Preact support", () => {
   });
 });
 
+describe("useSyncExternalStore shim", () => {
+  test("re-renders when the store mutates between render and layout effect", async () => {
+    // the internal shim is untyped, it mirrors the React useSyncExternalStore signature
+    const { useSyncExternalStore } = (await import(
+      // @ts-expect-error
+      "../src/react-deps.js"
+    )) as {
+      useSyncExternalStore: <T>(
+        subscribe: (cb: () => void) => () => void,
+        getSnapshot: () => T,
+        getSSRSnapshot?: () => T
+      ) => T;
+    };
+    const { useLayoutEffect } = await import("preact/hooks");
+
+    let value = "initial";
+    const listeners = new Set<() => void>();
+    const subscribe = (cb: () => void) => {
+      listeners.add(cb);
+      return () => listeners.delete(cb);
+    };
+
+    // child layout effects run before the parent's, so this mutation happens
+    // after the parent has rendered but before its layout effect compares snapshots
+    const Child = () => {
+      useLayoutEffect(() => {
+        value = "mutated";
+      }, []);
+      return null;
+    };
+
+    const Parent = () => {
+      const snapshot = useSyncExternalStore(subscribe, () => value);
+      return (
+        <div data-testid="snapshot">
+          {snapshot}
+          <Child />
+        </div>
+      );
+    };
+
+    const container = document.body.appendChild(document.createElement("div"));
+    act(() => {
+      render(<Parent />, container);
+    });
+
+    expect(container.textContent).toBe("mutated");
+  });
+});
+
 describe("Preact SSR", () => {
   test.skip("supports SSR (fix: useSyncExternalStore polyfill in Bun)", async () => {
     const { Router, useLocation } = await loadPreact();

packages/wouter/test/setup.ts

@@ -13,6 +13,12 @@ GlobalRegistrator.register({
 // Extend Bun's expect with jest-dom matchers
 (expect as any).extend(matchers);
 
+// Load the library first so the history monkey-patch in use-browser-location.js
+// is applied (and attributed) to this copy of the module, not the temporary
+// wouter-preact copy created by preact.test.tsx. Must run after happy-dom
+// registration, hence a dynamic import.
+await import("../src/use-browser-location.js");
+
 /**
  * Runs a function with `location` temporarily removed from globalThis.
  * Simulates pure Node.js SSR environment for testing.

packages/wouter/test/use-search.test.tsx

@@ -11,6 +11,14 @@ test("returns browser search string", () => {
   expect(result.current).toEqual("active=true");
 });
 
+test("returns search string as-is when it contains malformed escapes", () => {
+  history.replaceState(null, "", "/users?q=100%");
+  const { result } = renderHook(() => useSearch());
+
+  // decodeURI throws on "%", sanitizeSearch falls back to the raw string
+  expect(result.current).toEqual("q=100%");
+});
+
 test("can be customized in the Router", () => {
   const customSearchHook = ({ customOption = "unused" }) => "none";