fix(url): ensure toDecode involved in cache match;

- Related: sveltejs/kit#2166

packages/url/index.js

@@ -21,8 +21,8 @@ export function parse(req, toDecode) {
 	let raw = req.url;
 	if (raw == null) return;
 
-	let prev = req._parsedUrl;
-	if (prev && prev.raw === raw) return prev;
+	let prev=req._parsedUrl, encoded=!req._decoded;
+	if (prev && prev.raw === raw && !toDecode === encoded) return prev;
 
 	let pathname=raw, search='', query;
 
@@ -37,7 +37,7 @@ export function parse(req, toDecode) {
 			}
 		}
 
-		if (!!toDecode && !req._decoded) {
+		if (!!toDecode && encoded) {
 			req._decoded = true;
 			if (pathname.indexOf('%') !== -1) {
 				try { pathname = decodeURIComponent(pathname) }

packages/url/test/index.js

@@ -210,4 +210,60 @@ test('url :: decode :: URI malformed', () => {
 	});
 });
 
+test('url :: decode :: cache :: hit', () => {
+	/** @type any */
+	let req = { url: '/foo/hell%C3%B6' };
+	let out1 = parse(req, true);
+
+	// @ts-ignore
+	out1.foobar = 123;
+
+	let out2 = parse(req, true);
+
+	// @ts-ignore
+	assert.is(out2.foobar, 123);
+	assert.is(out1, out2, 'referential');
+	assert.is(out1.pathname, '/foo/hellö');
+});
+
+test('url :: decode :: cache :: miss #1', () => {
+	/** @type any */
+	let req = { url: '/foo/hell%C3%B6?fizz=buzz' };
+	let out1 = parse(req);
+
+	assert.is(req._parsedUrl, out1);
+	assert.is(out1.pathname, '/foo/hell%C3%B6');
+
+	// @ts-ignore
+	out1.foobar = 123;
+
+	let out2 = parse(req, true);
+
+	// @ts-ignore
+	assert.is(out2.foobar, undefined);
+	assert.is.not(req._parsedUrl, out1);
+	assert.is.not(out1, out2, 'referential');
+	assert.is(out2.pathname, '/foo/hellö');
+});
+
+test('url :: decode :: cache :: miss #2', () => {
+	/** @type any */
+	let req = { url: '/foo/hell%C3%B6?fizz=buzz' };
+	let out1 = parse(req, true);
+
+	assert.is(req._parsedUrl, out1);
+	assert.is(out1.pathname, '/foo/hellö');
+
+	// @ts-ignore
+	out1.foobar = 123;
+
+	let out2 = parse(req);
+
+	// @ts-ignore
+	assert.is(out2.foobar, undefined);
+	assert.is.not(req._parsedUrl, out1);
+	assert.is.not(out1, out2, 'referential');
+	assert.is(out2.pathname, '/foo/hell%C3%B6');
+});
+
 test.run();