Added hasFeature email template helper (#20271)

refs
https://ghost.slack.com/archives/C06TQR9SHSM/p1716816764653789?thread_ts=1716795330.737919&cid=C06TQR9SHSM MOM-158

- adds a new `hasFeature` helper for adding content behind a flag within
Email Templates.
- Usage: `{{#hasFeature 'flagname'}} <p>html behind flag</p>
{{/hasFeature}}`
- Added additional testing for testing the helpers

ghost/email-service/lib/EmailRenderer.js

@@ -10,6 +10,7 @@ const htmlToPlaintext = require('@tryghost/html-to-plaintext');
 const tpl = require('@tryghost/tpl');
 const cheerio = require('cheerio');
 const {EmailAddressParser} = require('@tryghost/email-addresses');
+const {registerHelpers} = require('./helpers/register-helpers');
 
 const messages = {
     subscriptionStatus: {
@@ -755,53 +756,16 @@ class EmailRenderer {
         return replacements;
     }
 
+    getLabs() {
+        return this.#labs;
+    }
+
     async renderTemplate(data) {
+        const labs = this.getLabs();
         this.#handlebars = require('handlebars').create();
 
-        // Helpers
+        // Register helpers
-        this.#handlebars.registerHelper('if', function (conditional, options) {
+        registerHelpers(this.#handlebars, labs);
-            if (conditional) {
-                return options.fn(this);
-            } else {
-                return options.inverse(this);
-            }
-        });
-
-        this.#handlebars.registerHelper('and', function () {
-            const len = arguments.length - 1;
-
-            for (let i = 0; i < len; i++) {
-                if (!arguments[i]) {
-                    return false;
-                }
-            }
-
-            return true;
-        });
-
-        this.#handlebars.registerHelper('not', function () {
-            const len = arguments.length - 1;
-
-            for (let i = 0; i < len; i++) {
-                if (!arguments[i]) {
-                    return true;
-                }
-            }
-
-            return false;
-        });
-
-        this.#handlebars.registerHelper('or', function () {
-            const len = arguments.length - 1;
-
-            for (let i = 0; i < len; i++) {
-                if (arguments[i]) {
-                    return true;
-                }
-            }
-
-            return false;
-        });
 
         // Partials
         if (this.#labs.isSet('emailCustomization')) {

ghost/email-service/lib/helpers/register-helpers.js

@@ -0,0 +1,55 @@
+module.exports = {
+    registerHelpers(handlebars, labs) {
+        handlebars.registerHelper('if', function (conditional, options) {
+            if (conditional) {
+                return options.fn(this);
+            } else {
+                return options.inverse(this);
+            }
+        });
+
+        handlebars.registerHelper('and', function () {
+            const len = arguments.length - 1;
+
+            for (let i = 0; i < len; i++) {
+                if (!arguments[i]) {
+                    return false;
+                }
+            }
+
+            return true;
+        });
+
+        handlebars.registerHelper('not', function () {
+            const len = arguments.length - 1;
+
+            for (let i = 0; i < len; i++) {
+                if (!arguments[i]) {
+                    return true;
+                }
+            }
+
+            return false;
+        });
+
+        handlebars.registerHelper('or', function () {
+            const len = arguments.length - 1;
+
+            for (let i = 0; i < len; i++) {
+                if (arguments[i]) {
+                    return true;
+                }
+            }
+
+            return false;
+        });
+
+        handlebars.registerHelper('hasFeature', function (flag, options) {
+            if (labs.isSet(flag)) {
+                return options.fn(this);
+            } else {
+                return options.inverse(this);
+            }
+        });
+    }
+};

ghost/email-service/test/email-helpers.test.js

@@ -0,0 +1,142 @@
+const assert = require('assert/strict');
+const {registerHelpers} = require('../lib/helpers/register-helpers');
+
+describe('registerHelpers', function () {
+    it('registers helpers', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return true;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        assert.ok(handlebars.if);
+        assert.ok(handlebars.and);
+        assert.ok(handlebars.not);
+        assert.ok(handlebars.or);
+        assert.ok(handlebars.hasFeature);
+    });
+
+    it('if helper returns true', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return true;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        const result = handlebars.if(true, {
+            fn: function () {
+                return true;
+            },
+            inverse: function () {
+                return false;
+            }
+        });
+
+        assert.equal(result, true);
+    });
+
+    it('if helper returns false', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return true;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        const result = handlebars.if(false, {
+            fn: function () {
+                return true;
+            },
+            inverse: function () {
+                return false;
+            }
+        });
+
+        assert.equal(result, false);
+    });
+
+    it('and helper returns true', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return true;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        const result = handlebars.and(true, true);
+
+        assert.equal(result, true);
+    });
+
+    it('usefeature helper returns true', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return true;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        const result = handlebars.hasFeature('test', {
+            fn: function () {
+                return true;
+            },
+            inverse: function () {
+                return false;
+            }
+        });
+
+        assert.equal(result, true);
+    });
+
+    it('usefeature helper returns false', function () {
+        const handlebars = {
+            registerHelper: function (name, fn) {
+                this[name] = fn;
+            }
+        };
+        const labs = {
+            isSet: function () {
+                return false;
+            }
+        };
+        registerHelpers(handlebars, labs);
+
+        const result = handlebars.hasFeature('test', {
+            fn: function () {
+                return true;
+            },
+            inverse: function () {
+                return false;
+            }
+        });
+
+        assert.equal(result, false);
+    });
+});