1 files changed, 28 insertions, 2 deletions
diff --git a/js/url_search_params_test.ts b/js/url_search_params_test.ts
index 46e8103d9..802ab288b 100644
--- a/js/url_search_params_test.ts
+++ b/js/url_search_params_test.ts
@@ -59,11 +59,18 @@ test(function urlSearchParamsHasSuccess() {
   assert(!searchParams.has("c"));
 });
 
-test(function urlSearchParamsSetSuccess() {
+test(function urlSearchParamsSetReplaceFirstAndRemoveOthers() {
   const init = "a=54&b=true&a=true";
   const searchParams = new URLSearchParams(init);
   searchParams.set("a", "false");
-  assertEqual(searchParams.toString(), "b=true&a=false");
+  assertEqual(searchParams.toString(), "a=false&b=true");
+});
+
+test(function urlSearchParamsSetAppendNew() {
+  const init = "a=54&b=true&a=true";
+  const searchParams = new URLSearchParams(init);
+  searchParams.set("c", "foo");
+  assertEqual(searchParams.toString(), "a=54&b=true&a=true&c=foo");
 });
 
 test(function urlSearchParamsSortSuccess() {
@@ -112,3 +119,22 @@ test(function urlSearchParamsMissingPair() {
   const searchParams = new URLSearchParams(init);
   assertEqual(searchParams.toString(), "c=4&a=54");
 });
+
+// If pair does not contain exactly two items, then throw a TypeError.
+// ref https://url.spec.whatwg.org/#interface-urlsearchparams
+test(function urlSearchParamsShouldThrowTypeError() {
+  let hasThrown = 0;
+
+  try {
+    new URLSearchParams([["1"]]);
+    hasThrown = 1;
+  } catch (err) {
+    if (err instanceof TypeError) {
+      hasThrown = 2;
+    } else {
+      hasThrown = 3;
+    }
+  }
+
+  assertEqual(hasThrown, 2);
+});