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/random.js

@@ -0,0 +1,104 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { MAX_INTEGER, stubTrue } from './utils.js';
+import random from '../random.js';
+
+describe('random', function() {
+  var array = Array(1000);
+
+  it('should return `0` or `1` when no arguments are given', function() {
+    var actual = lodashStable.uniq(lodashStable.map(array, function() {
+      return random();
+    })).sort();
+
+    assert.deepStrictEqual(actual, [0, 1]);
+  });
+
+  it('should support a `min` and `max`', function() {
+    var min = 5,
+        max = 10;
+
+    assert.ok(lodashStable.some(array, function() {
+      var result = random(min, max);
+      return result >= min && result <= max;
+    }));
+  });
+
+  it('should support not providing a `max`', function() {
+    var min = 0,
+        max = 5;
+
+    assert.ok(lodashStable.some(array, function() {
+      var result = random(max);
+      return result >= min && result <= max;
+    }));
+  });
+
+  it('should swap `min` and `max` when `min` > `max`', function() {
+    var min = 4,
+        max = 2,
+        expected = [2, 3, 4];
+
+    var actual = lodashStable.uniq(lodashStable.map(array, function() {
+      return random(min, max);
+    })).sort();
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  it('should support large integer values', function() {
+    var min = Math.pow(2, 31),
+        max = Math.pow(2, 62);
+
+    assert.ok(lodashStable.every(array, function() {
+      var result = random(min, max);
+      return result >= min && result <= max;
+    }));
+
+    assert.ok(lodashStable.some(array, function() {
+      return random(MAX_INTEGER);
+    }));
+  });
+
+  it('should coerce arguments to finite numbers', function() {
+    var actual = [
+      random(NaN, NaN),
+      random('1', '1'),
+      random(Infinity, Infinity)
+    ];
+
+    assert.deepStrictEqual(actual, [0, 1, MAX_INTEGER]);
+  });
+
+  it('should support floats', function() {
+    var min = 1.5,
+        max = 1.6,
+        actual = random(min, max);
+
+    assert.ok(actual % 1);
+    assert.ok(actual >= min && actual <= max);
+  });
+
+  it('should support providing a `floating`', function() {
+    var actual = random(true);
+    assert.ok(actual % 1 && actual >= 0 && actual <= 1);
+
+    actual = random(2, true);
+    assert.ok(actual % 1 && actual >= 0 && actual <= 2);
+
+    actual = random(2, 4, true);
+    assert.ok(actual % 1 && actual >= 2 && actual <= 4);
+  });
+
+  it('should work as an iteratee for methods like `_.map`', function() {
+    var array = [1, 2, 3],
+        expected = lodashStable.map(array, stubTrue),
+        randoms = lodashStable.map(array, random);
+
+    var actual = lodashStable.map(randoms, function(result, index) {
+      return result >= 0 && result <= array[index] && (result % 1) == 0;
+    });
+
+    assert.deepStrictEqual(actual, expected);
+  });
+});