diff --git a/js/testing/testing.ts b/js/testing/testing.ts
new file mode 100644
index 0000000000..828ebec2f0
--- /dev/null
+++ b/js/testing/testing.ts
@@ -0,0 +1,96 @@
+/*!
+   Copyright 2018 Propel http://propel.site/.  All rights reserved.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+export { assert, assertEqual, equal } from "./util.ts";
+
+export type TestFunction = () => void | Promise<void>;
+
+export interface TestDefinition {
+  fn: TestFunction;
+  name: string;
+}
+
+export const exitOnFail = true;
+
+/* A subset of the tests can be ran by providing a filter expression.
+ * In Node.js the filter is specified on the command line:
+ *
+ *   ts-node test_node log        # all tests with 'log' in the name
+ *   ts-node test_node ^util      # tests starting with 'util'
+ *
+ * In the browser, the filter is specified as part of the url:
+ *
+ *   http://localhost:9876/test.html#script=some/script.js&filter=log
+ *   http://localhost:9876/test.html#script=some/script.js&filter=^util
+ */
+let filterExpr: string = null;
+
+const filterRegExp = filterExpr ? new RegExp(filterExpr, "i") : null;
+const tests: TestDefinition[] = [];
+
+export function test(t: TestDefinition | TestFunction): void {
+  const fn: TestFunction = typeof t === "function" ? t : t.fn;
+  const name: string = t.name;
+
+  if (!name) {
+    throw new Error("Test function may not be anonymous");
+  }
+  if (filter(name)) {
+    tests.push({ fn, name });
+  }
+}
+
+function filter(name: string): boolean {
+  if (filterRegExp) {
+    return filterRegExp.test(name);
+  } else {
+    return true;
+  }
+}
+
+async function runTests() {
+  let passed = 0;
+  let failed = 0;
+
+  for (let i = 0; i < tests.length; i++) {
+    const { fn, name } = tests[i];
+    console.log(`${i + 1}/${tests.length} +${passed} -${failed}: ${name}`);
+    try {
+      await fn();
+      passed++;
+    } catch (e) {
+      console.error("\nTest FAIL", name);
+      console.error((e && e.stack) || e);
+      failed++;
+      if (exitOnFail) {
+        break;
+      }
+    }
+  }
+
+  console.log(`\nDONE. Test passed: ${passed}, failed: ${failed}`);
+
+  if (failed === 0) {
+    // All good.
+  } else {
+    // Use setTimeout to avoid the error being ignored due to unhandled
+    // promise rejections being swallowed.
+    setTimeout(() => {
+      throw new Error(`There were ${failed} test failures.`);
+    }, 0);
+  }
+}
+
+setTimeout(runTests, 0);
diff --git a/js/testing/util.ts b/js/testing/util.ts
new file mode 100644
index 0000000000..1935403516
--- /dev/null
+++ b/js/testing/util.ts
@@ -0,0 +1,64 @@
+/*!
+   Copyright 2018 Propel http://propel.site/.  All rights reserved.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+ */
+
+// TODO(ry) Use unknown here for parameters types.
+// tslint:disable-next-line:no-any
+export function assertEqual(actual: any, expected: any, msg?: string) {
+  if (!msg) {
+    msg = `actual: ${actual} expected: ${expected}`;
+  }
+  if (!equal(actual, expected)) {
+    console.error(
+      "assertEqual failed. actual = ",
+      actual,
+      "expected =",
+      expected
+    );
+    throw new Error(msg);
+  }
+}
+
+export function assert(expr: boolean, msg = "") {
+  if (!expr) {
+    throw new Error(msg);
+  }
+}
+
+// TODO(ry) Use unknown here for parameters types.
+// tslint:disable-next-line:no-any
+export function equal(c: any, d: any): boolean {
+  const seen = new Map();
+  return (function compare(a, b) {
+    if (Object.is(a, b)) {
+      return true;
+    }
+    if (a && typeof a === "object" && b && typeof b === "object") {
+      if (seen.get(a) === b) {
+        return true;
+      }
+      if (Object.keys(a).length !== Object.keys(b).length) {
+        return false;
+      }
+      for (const key in { ...a, ...b }) {
+        if (!compare(a[key], b[key])) {
+          return false;
+        }
+      }
+      seen.set(a, b);
+      return true;
+    }
+    return false;
+  })(c, d);
+}
diff --git a/js/testing/util_test.ts b/js/testing/util_test.ts
new file mode 100644
index 0000000000..9ac3dfd71b
--- /dev/null
+++ b/js/testing/util_test.ts
@@ -0,0 +1,40 @@
+/*!
+   Copyright 2018 Propel http://propel.site/.  All rights reserved.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+ */
+
+import { test } from "./testing.ts";
+import { assert } from "./util.ts";
+import * as util from "./util.ts";
+
+test(async function util_equal() {
+  assert(util.equal("world", "world"));
+  assert(!util.equal("hello", "world"));
+  assert(util.equal(5, 5));
+  assert(!util.equal(5, 6));
+  assert(util.equal(NaN, NaN));
+  assert(util.equal({ hello: "world" }, { hello: "world" }));
+  assert(!util.equal({ world: "hello" }, { hello: "world" }));
+  assert(
+    util.equal(
+      { hello: "world", hi: { there: "everyone" } },
+      { hello: "world", hi: { there: "everyone" } }
+    )
+  );
+  assert(
+    !util.equal(
+      { hello: "world", hi: { there: "everyone" } },
+      { hello: "world", hi: { there: "everyone else" } }
+    )
+  );
+});
diff --git a/js/tests.ts b/js/unit_tests.ts
similarity index 85%
rename from js/tests.ts
rename to js/unit_tests.ts
index 3e8be12a19..6989e22c4f 100644
--- a/js/tests.ts
+++ b/js/unit_tests.ts
@@ -2,59 +2,14 @@
 // This test is executed as part of integration_test.go
 // But it can also be run manually:
 //  ./deno tests.ts
-// There must also be a static file http server running on localhost:4545
-// serving the deno project directory. Try this:
-//   http-server -p 4545 --cors .
+
 import { test, assert, assertEqual } from "./testing/testing.ts";
-import { readFileSync, writeFileSync } from "deno";
+// import { readFileSync, writeFileSync } from "deno";
 
 test(async function tests_test() {
   assert(true);
 });
 
-test(async function tests_fetch() {
-  const response = await fetch("http://localhost:4545/package.json");
-  const json = await response.json();
-  assertEqual(json.name, "deno");
-});
-
-test(function tests_console_assert() {
-  console.assert(true);
-
-  let hasThrown = false;
-  try {
-    console.assert(false);
-  } catch {
-    hasThrown = true;
-  }
-  assertEqual(hasThrown, true);
-});
-
-test(async function tests_readFileSync() {
-  const data = readFileSync("package.json");
-  if (!data.byteLength) {
-    throw Error(
-      `Expected positive value for data.byteLength ${data.byteLength}`
-    );
-  }
-  const decoder = new TextDecoder("utf-8");
-  const json = decoder.decode(data);
-  const pkg = JSON.parse(json);
-  assertEqual(pkg.name, "deno");
-});
-
-test(async function tests_writeFileSync() {
-  const enc = new TextEncoder();
-  const data = enc.encode("Hello");
-  // TODO need ability to get tmp dir.
-  // const fn = "/tmp/test.txt";
-  writeFileSync("/tmp/test.txt", data, 0o666);
-  const dataRead = readFileSync("/tmp/test.txt");
-  const dec = new TextDecoder("utf-8");
-  const actual = dec.decode(dataRead);
-  assertEqual("Hello", actual);
-});
-
 test(function tests_console_assert() {
   console.assert(true);
 
@@ -123,3 +78,37 @@ test(function tests_console_stringify_circular() {
     throw new Error("Expected no crash on circular object");
   }
 });
+
+/*
+test(async function tests_fetch() {
+  const response = await fetch("http://localhost:4545/package.json");
+  const json = await response.json();
+  assertEqual(json.name, "deno");
+});
+
+test(async function tests_readFileSync() {
+  const data = readFileSync("package.json");
+  if (!data.byteLength) {
+    throw Error(
+      `Expected positive value for data.byteLength ${data.byteLength}`
+    );
+  }
+  const decoder = new TextDecoder("utf-8");
+  const json = decoder.decode(data);
+  const pkg = JSON.parse(json);
+  assertEqual(pkg.name, "deno");
+});
+
+test(async function tests_writeFileSync() {
+  const enc = new TextEncoder();
+  const data = enc.encode("Hello");
+  // TODO need ability to get tmp dir.
+  const fn = "/tmp/test.txt";
+  writeFileSync("/tmp/test.txt", data, 0o666);
+  const dataRead = readFileSync("/tmp/test.txt");
+  const dec = new TextDecoder("utf-8");
+  const actual = dec.decode(dataRead);
+  assertEqual("Hello", actual);
+});
+
+*/
diff --git a/tools/test.py b/tools/test.py
index 3edfa4e015..91557e0fdc 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -4,21 +4,24 @@
 import os
 import sys
 from check_output_test import check_output_test
-from util import executable_suffix, run
+from util import executable_suffix, run, build_path
 
 
 def check_exists(filename):
     if not os.path.exists(filename):
         print "Required target doesn't exist:", filename
-        print "Build target :all"
+        print "Run ./tools/build.py"
         sys.exit(1)
 
 
 def main(argv):
-    if len(argv) != 2:
-        print "Usage: tools/test.py [build dir]"
+    if len(argv) == 2:
+        build_dir = sys.argv[1]
+    elif len(argv) == 1:
+        build_dir = build_path()
+    else:
+        print "Usage: tools/test.py [build_dir]"
         sys.exit(1)
-    build_dir = argv[1]
 
     test_cc = os.path.join(build_dir, "test_cc" + executable_suffix)
     check_exists(test_cc)
@@ -29,6 +32,9 @@ def main(argv):
     run([test_rs])
 
     deno_exe = os.path.join(build_dir, "deno" + executable_suffix)
+    check_exists(deno_exe)
+    run([deno_exe, "js/unit_tests.ts"])
+
     check_exists(deno_exe)
     check_output_test(deno_exe)