Add `.find` poly

2 files changed, 46 insertions, 23 deletions

diff --git a/spec/javascripts/extensions/array_spec.js b/spec/javascripts/extensions/array_spec.js
deleted file mode 100644
index c56e6c7789b..00000000000
--- a/spec/javascripts/extensions/array_spec.js
+++ /dev/null
@@ -1,23 +0,0 @@
-/* eslint-disable space-before-function-paren, no-var, padded-blocks */
-
-/*= require extensions/array */
-
-(function() {
-  describe('Array extensions', function() {
-    describe('first', function() {
-      return it('returns the first item', function() {
-        var arr;
-        arr = [0, 1, 2, 3, 4, 5];
-        return expect(arr.first()).toBe(0);
-      });
-    });
-    return describe('last', function() {
-      return it('returns the last item', function() {
-        var arr;
-        arr = [0, 1, 2, 3, 4, 5];
-        return expect(arr.last()).toBe(5);
-      });
-    });
-  });
-
-}).call(this);
diff --git a/spec/javascripts/extensions/array_spec.js.es6 b/spec/javascripts/extensions/array_spec.js.es6
new file mode 100644
index 00000000000..2ec759c8e80
--- /dev/null
+++ b/spec/javascripts/extensions/array_spec.js.es6
@@ -0,0 +1,46 @@
+/* eslint-disable space-before-function-paren, no-var, padded-blocks */
+
+/*= require extensions/array */
+
+(function() {
+  describe('Array extensions', function() {
+    describe('first', function() {
+      return it('returns the first item', function() {
+        var arr;
+        arr = [0, 1, 2, 3, 4, 5];
+        return expect(arr.first()).toBe(0);
+      });
+    });
+    describe('last', function() {
+      return it('returns the last item', function() {
+        var arr;
+        arr = [0, 1, 2, 3, 4, 5];
+        return expect(arr.last()).toBe(5);
+      });
+    });
+
+    describe('find', function () {
+      beforeEach(() => {
+        this.arr = [0, 1, 2, 3, 4, 5];
+      });
+
+      it('returns the item that first passes the predicate function', () => {
+        expect(this.arr.find(item => item === 2)).toBe(2);
+      });
+
+      it('returns undefined if no items pass the predicate function', () => {
+        expect(this.arr.find(item => item === 6)).not.toBeDefined();
+      });
+
+      it('error when called on undefined or null', () => {
+        expect(Array.prototype.find.bind(undefined, item => item === 1)).toThrow();
+        expect(Array.prototype.find.bind(null, item => item === 1)).toThrow();
+      });
+
+      it('error when predicate is not a function', () => {
+        expect(Array.prototype.find.bind(this.arr, 1)).toThrow();
+      });
+    });
+  });
+
+}).call(this);