test: improve coverage of ModuleMap.js

PR-URL: https://github.com/nodejs/node/pull/15924
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-internal-module-map-asserts.js

@@ -0,0 +1,44 @@
+// Flags: --expose-internals
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const ModuleMap = require('internal/loader/ModuleMap');
+
+// ModuleMap.get, ModuleMap.has and  ModuleMap.set should only accept string
+// values as url argument.
+{
+  const errorReg = common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    type: TypeError,
+    message: /^The "url" argument must be of type string/
+  }, 15);
+
+  const moduleMap = new ModuleMap();
+
+  // As long as the assertion of "job" argument is done after the assertion of
+  // "url" argument this test suite is ok.  Tried to mock the "job" parameter,
+  // but I think it's useless, and was not simple to mock...
+  const job = undefined;
+
+  [{}, [], true, 1, () => {}].forEach((value) => {
+    assert.throws(() => moduleMap.get(value), errorReg);
+    assert.throws(() => moduleMap.has(value), errorReg);
+    assert.throws(() => moduleMap.set(value, job), errorReg);
+  });
+}
+
+// ModuleMap.set, job argument should only accept ModuleJob values.
+{
+  const errorReg = common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    type: TypeError,
+    message: /^The "job" argument must be of type ModuleJob/
+  }, 5);
+
+  const moduleMap = new ModuleMap();
+
+  [{}, [], true, 1, () => {}].forEach((value) => {
+    assert.throws(() => moduleMap.set('', value), errorReg);
+  });
+}