feat(check): turn on noImplicitOverride (#25695)

Closes https://github.com/denoland/deno/issues/11836

Ref https://github.com/denoland/deno/issues/25162

4 files changed, 19 insertions, 2 deletions

diff --git a/tests/specs/check/no_implicit_override/__test__.jsonc b/tests/specs/check/no_implicit_override/__test__.jsonc
new file mode 100644
index 000000000..a991c6eed
--- /dev/null
+++ b/tests/specs/check/no_implicit_override/__test__.jsonc
@@ -0,0 +1,5 @@
+{
+  "args": "check main.ts",
+  "output": "main.out",
+  "exitCode": 1
+}
diff --git a/tests/specs/check/no_implicit_override/main.out b/tests/specs/check/no_implicit_override/main.out
new file mode 100644
index 000000000..6fd657341
--- /dev/null
+++ b/tests/specs/check/no_implicit_override/main.out
@@ -0,0 +1,5 @@
+Check file:///[WILDCARD]/main.ts
+error: TS4114 [ERROR]: This member must have an 'override' modifier because it overrides a member in the base class 'Greet'.
+  greet() {}
+  ~~~~~
+    at file:///[WILDCARD]/no_implicit_override/main.ts:6:3
diff --git a/tests/specs/check/no_implicit_override/main.ts b/tests/specs/check/no_implicit_override/main.ts
new file mode 100644
index 000000000..b51dfb9d9
--- /dev/null
+++ b/tests/specs/check/no_implicit_override/main.ts
@@ -0,0 +1,7 @@
+class Greet {
+  greet() {}
+}
+
+class Welcome extends Greet {
+  greet() {}
+}
diff --git a/tests/unit/url_search_params_test.ts b/tests/unit/url_search_params_test.ts
index c547ef938..d682c291a 100644
--- a/tests/unit/url_search_params_test.ts
+++ b/tests/unit/url_search_params_test.ts
@@ -330,7 +330,7 @@ Deno.test(
   function urlSearchParamsOverridingAppendNotChangeConstructorAndSet() {
     let overriddenAppendCalled = 0;
     class CustomSearchParams extends URLSearchParams {
-      append(name: string, value: string) {
+      override append(name: string, value: string) {
         ++overriddenAppendCalled;
         super.append(name, value);
       }
@@ -345,7 +345,7 @@ Deno.test(
 
 Deno.test(function urlSearchParamsOverridingEntriesNotChangeForEach() {
   class CustomSearchParams extends URLSearchParams {
-    *entries(): IterableIterator<[string, string]> {
+    override *entries(): IterableIterator<[string, string]> {
       yield* [];
     }
   }