feat: adding includes helper for templating (#28148)

docs/usage/templates.md

@@ -110,6 +110,12 @@ Returns `true` if at least one expression is `true`.
 
 `{{#if (or isPatch isSingleVersion}}Small update, safer to merge and release.{{else}}Check out the changelog for all versions before merging!{{/if}}`
 
+### includes
+
+Returns `true` if the value is included on the list given.
+
+`{{#if (includes labels 'dependencies')}}Production Dependencies{{else}}Not Production Dependencies{{/if}}`
+
 ## Environment variables
 
 By default, you can only access a handful of basic environment variables like `HOME` or `PATH`.

lib/util/template/index.spec.ts

@@ -276,4 +276,50 @@ describe('util/template/index', () => {
       expect(output).toBe('not equals');
     });
   });
+
+  describe('includes', () => {
+    it('includes is true', () => {
+      const output = template.compile(
+        '{{#if (includes labels "dependencies")}}production{{else}}notProduction{{/if}}',
+        {
+          labels: ['dependencies'],
+        },
+      );
+
+      expect(output).toBe('production');
+    });
+
+    it('includes is false', () => {
+      const output = template.compile(
+        '{{#if (includes labels "dependencies")}}production{{else}}notProduction{{/if}}',
+        {
+          labels: ['devDependencies'],
+        },
+      );
+
+      expect(output).toBe('notProduction');
+    });
+
+    it('includes with incorrect type first argument', () => {
+      const output = template.compile(
+        '{{#if (includes labels "dependencies")}}production{{else}}notProduction{{/if}}',
+        {
+          labels: 'devDependencies',
+        },
+      );
+
+      expect(output).toBe('notProduction');
+    });
+
+    it('includes with incorrect type second argument', () => {
+      const output = template.compile(
+        '{{#if (includes labels 555)}}production{{else}}notProduction{{/if}}',
+        {
+          labels: ['devDependencies'],
+        },
+      );
+
+      expect(output).toBe('notProduction');
+    });
+  });
 });

lib/util/template/index.ts

@@ -28,6 +28,14 @@ handlebars.registerHelper('containsString', (str, subStr) =>
 
 handlebars.registerHelper('equals', (arg1, arg2) => arg1 === arg2);
 
+handlebars.registerHelper('includes', (arg1: string[], arg2: string) => {
+  if (is.array(arg1, is.string) && is.string(arg2)) {
+    return arg1.includes(arg2);
+  }
+
+  return false;
+});
+
 handlebars.registerHelper({
   and(...args) {
     // Need to remove the 'options', as last parameter