Implement childExpect#exportStyle

lib/Unexpected.js

@@ -1352,6 +1352,13 @@ Unexpected.prototype.child = function () {
         parent.addType(type, childUnexpected);
         return this;
     };
+    childExpect.exportStyle = function (name, handler) {
+        parent.addStyle(name, function () { // ...
+            var childOutput = childExpect.createOutput(this.format);
+            this.append(handler.apply(childOutput, arguments) || childOutput);
+        });
+        return this;
+    };
     return childExpect;
 };
 

test/api/exportStyle.spec.js

@@ -0,0 +1,46 @@
+/*global expect*/
+describe('styleType', function () {
+    var parentExpect;
+    var childExpect;
+    beforeEach(function () {
+        parentExpect = expect.clone();
+        childExpect = parentExpect.child();
+    });
+
+    it('is chainable', function () {
+        childExpect
+            .exportStyle('firstStyle', function () {})
+            .exportStyle('secondStyle', function () {});
+
+        expect(parentExpect.output.firstStyle, 'to be a function');
+        expect(parentExpect.output.secondStyle, 'to be a function');
+    });
+
+    it('makes the style available to the parent expect', function () {
+        childExpect.exportStyle('fancyQuotes', function (text) {
+            this.text('>>').text(text).text('<<');
+        });
+
+        expect(
+            parentExpect.createOutput().fancyQuotes('yadda').toString(),
+            'to equal',
+            '>>yadda<<'
+        );
+    });
+
+    it('binds the style handler to a child expect output so custom types are available inside the exported style', function () {
+        childExpect.addStyle('fancyQuotes', function (text) {
+            this.text('>>').text(text).text('<<');
+        });
+
+        childExpect.exportStyle('emphasize', function (text) {
+            this.fancyQuotes(text);
+        });
+
+        expect(
+            parentExpect.createOutput().emphasize('yadda').toString(),
+            'to equal',
+            '>>yadda<<'
+        );
+    });
+});