1 files changed, 15 insertions, 0 deletions
diff --git a/std/_util/assert.ts b/std/_util/assert.ts
new file mode 100644
index 000000000..d797591fe
--- /dev/null
+++ b/std/_util/assert.ts
@@ -0,0 +1,15 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+export class DenoStdInternalError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "DenoStdInternalError";
+  }
+}
+
+/** Make an assertion, if not `true`, then throw. */
+export function assert(expr: unknown, msg = ""): asserts expr {
+  if (!expr) {
+    throw new DenoStdInternalError(msg);
+  }
+}