1 files changed, 10 insertions, 0 deletions
diff --git a/testing/asserts.ts b/testing/asserts.ts
index 233219b6a..6431a11a5 100644
--- a/testing/asserts.ts
+++ b/testing/asserts.ts
@@ -283,3 +283,13 @@ export async function assertThrowsAsync(
     throw new Error(msg);
   }
 }
+
+/** Use this to stub out methods that will throw when invoked. */
+export function unimplemented(msg?: string): never {
+  throw new Error(msg || "unimplemented");
+}
+
+/** Use this to assert unreachable code. */
+export function unreachable(): never {
+  throw new Error("unreachable");
+}