Add initial test files from lodash v4. (#4172)

* Install test dependencies.

* Add initial test files.

These files were created using a simplistic AST manipulator using `recast` to
preserve formatting. There's bound to be a huge chunk of errors, but this serves
as a good start. QUnit was replaced with Mocha, with ES2015 imports running via
`esm`.

As far as possible, QUnit-specific syntax has been replaced with Mocha's
`describe` and `it`, while the native Node.js `assert` module is used for
assertions. Files in the `test` directory ending in `.test.js` will be treated
as test files.

* Add initial passing files to test run.

test/max.js

@@ -0,0 +1,27 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { falsey, noop } from './utils.js';
+import max from '../max.js';
+
+describe('max', function() {
+  it('should return the largest value from a collection', function() {
+    assert.strictEqual(max([1, 2, 3]), 3);
+  });
+
+  it('should return `undefined` for empty collections', function() {
+    var values = falsey.concat([[]]),
+        expected = lodashStable.map(values, noop);
+
+    var actual = lodashStable.map(values, function(value, index) {
+      try {
+        return index ? max(value) : max();
+      } catch (e) {}
+    });
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  it('should work with non-numeric collection values', function() {
+    assert.strictEqual(max(['a', 'b']), 'b');
+  });
+});