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/take.js

@@ -0,0 +1,65 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { falsey, LARGE_ARRAY_SIZE, isEven } from './utils.js';
+import take from '../take.js';
+
+describe('take', function() {
+  var array = [1, 2, 3];
+
+  it('should take the first two elements', function() {
+    assert.deepStrictEqual(take(array, 2), [1, 2]);
+  });
+
+  it('should treat falsey `n` values, except `undefined`, as `0`', function() {
+    var expected = lodashStable.map(falsey, function(value) {
+      return value === undefined ? [1] : [];
+    });
+
+    var actual = lodashStable.map(falsey, function(n) {
+      return take(array, n);
+    });
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  it('should return an empty array when `n` < `1`', function() {
+    lodashStable.each([0, -1, -Infinity], function(n) {
+      assert.deepStrictEqual(take(array, n), []);
+    });
+  });
+
+  it('should return all elements when `n` >= `length`', function() {
+    lodashStable.each([3, 4, Math.pow(2, 32), Infinity], function(n) {
+      assert.deepStrictEqual(take(array, n), array);
+    });
+  });
+
+  it('should work as an iteratee for methods like `_.map`', function() {
+    var array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]],
+        actual = lodashStable.map(array, take);
+
+    assert.deepStrictEqual(actual, [[1], [4], [7]]);
+  });
+
+  it('should work in a lazy sequence', function() {
+    var array = lodashStable.range(1, LARGE_ARRAY_SIZE + 1),
+        predicate = function(value) { values.push(value); return isEven(value); },
+        values = [],
+        actual = _(array).take(2).take().value();
+
+    assert.deepEqual(actual, take(take(array, 2)));
+
+    actual = _(array).filter(predicate).take(2).take().value();
+    assert.deepEqual(values, [1, 2]);
+    assert.deepEqual(actual, take(take(_.filter(array, predicate), 2)));
+
+    actual = _(array).take(6).takeRight(4).take(2).takeRight().value();
+    assert.deepEqual(actual, _.takeRight(take(_.takeRight(take(array, 6), 4), 2)));
+
+    values = [];
+
+    actual = _(array).take(array.length - 1).filter(predicate).take(6).takeRight(4).take(2).takeRight().value();
+    assert.deepEqual(values, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
+    assert.deepEqual(actual, _.takeRight(take(_.takeRight(take(_.filter(take(array, array.length - 1), predicate), 6), 4), 2)));
+  });
+});