support preserve tag (Closure Compiler only) (#605)

lib/jsdoc/tag/dictionary/definitions.js

@@ -931,6 +931,8 @@ exports.closureTags = {
     polymerBehavior: {
         onTagged: ignore
     },
+    // Closure Compiler only
+    preserve: cloneTagDef(baseTags.license),
     private: {
         canHaveType: true,
         onTagged: function(doclet, tag) {

test/fixtures/preservetag.js

@@ -0,0 +1,2 @@
+/** @preserve My cool license goes here. */
+var x;

test/specs/tags/preservetag.js

@@ -0,0 +1,43 @@
+'use strict';
+
+describe('@preserve tag', function() {
+    var env = require('jsdoc/env');
+    var logger = require('jsdoc/util/logger');
+
+    var allowUnknownTags = Boolean(env.conf.tags.allowUnknownTags);
+
+    beforeEach(function() {
+        env.conf.tags.allowUnknownTags = false;
+        spyOn(logger, 'error');
+    });
+
+    afterEach(function() {
+        jasmine.restoreTagDictionary();
+        env.conf.tags.allowUnknownTags = allowUnknownTags;
+    });
+
+    describe('JSDoc tags', function() {
+        beforeEach(function() {
+            jasmine.replaceTagDictionary('jsdoc');
+        });
+
+        it('should not recognize the @preserve tag', function() {
+            jasmine.getDocSetFromFile('test/fixtures/preservetag.js');
+
+            expect(logger.error).toHaveBeenCalled();
+        });
+    });
+
+    describe('Closure Compiler tags', function() {
+        beforeEach(function() {
+            jasmine.replaceTagDictionary('closure');
+        });
+
+        it('should set the doclet\'s `license` property to the tag value', function() {
+            var docSet = jasmine.getDocSetFromFile('test/fixtures/preservetag.js');
+            var x = docSet.getByLongname('x')[0];
+
+            expect(x.license).toBe('My cool license goes here.');
+        });
+    });
+});