Add new matcher for interpolated strings

- matcher
- matchers test

spec/frontend/matchers.js

@@ -35,4 +35,37 @@ export default {
       message: () => message,
     };
   },
+  toMatchInterpolatedText(received, match) {
+    let clearReceived;
+    let clearMatch;
+
+    try {
+      clearReceived = received
+        .replace(/\s\s+/gm, ' ')
+        .replace(/\s\./gm, '.')
+        .trim();
+    } catch (e) {
+      return { actual: received, message: 'The received value is not a string', pass: false };
+    }
+    try {
+      clearMatch = match.replace(/%{\w+}/gm, '').trim();
+    } catch (e) {
+      return { message: 'The comparator value is not a string', pass: false };
+    }
+    const pass = clearReceived === clearMatch;
+    const message = pass
+      ? () => `
+          \n\n
+          Expected: ${this.utils.printExpected(clearReceived)}
+          To not equal: ${this.utils.printReceived(clearMatch)}
+          `
+      : () =>
+          `
+        \n\n
+        Expected: ${this.utils.printExpected(clearReceived)}
+        To equal: ${this.utils.printReceived(clearMatch)}
+        `;
+
+    return { actual: received, message, pass };
+  },
 };

spec/frontend/matchers_spec.js

+describe('Custom jest matchers', () => {
+  describe('toMatchInterpolatedText', () => {
+    describe('malformed input', () => {
+      it.each([null, 1, Symbol, Array, Object])(
+        'fails graciously if the expected value is %s',
+        expected => {
+          expect(expected).not.toMatchInterpolatedText('null');
+        },
+      );
+    });
+    describe('malformed matcher', () => {
+      it.each([null, 1, Symbol, Array, Object])(
+        'fails graciously if the matcher is %s',
+        matcher => {
+          expect('null').not.toMatchInterpolatedText(matcher);
+        },
+      );
+    });
+
+    describe('positive assertion', () => {
+      it.each`
+        htmlString         | templateString
+        ${'foo'}           | ${'foo'}
+        ${'foo'}           | ${'foo%{foo}'}
+        ${'foo  '}         | ${'foo'}
+        ${'foo  '}         | ${'foo%{foo}'}
+        ${'foo   . '}      | ${'foo%{foo}.'}
+        ${'foo   bar . '}  | ${'foo%{foo} bar.'}
+        ${'foo\n\nbar . '} | ${'foo%{foo} bar.'}
+        ${'foo bar . .'}   | ${'foo%{fooStart} bar.%{fooEnd}.'}
+      `('$htmlString equals $templateString', ({ htmlString, templateString }) => {
+        expect(htmlString).toMatchInterpolatedText(templateString);
+      });
+    });
+
+    describe('negative assertion', () => {
+      it.each`
+        htmlString  | templateString
+        ${'foo'}    | ${'bar'}
+        ${'foo'}    | ${'bar%{foo}'}
+        ${'foo'}    | ${'@{lol}foo%{foo}'}
+        ${' fo o '} | ${'foo'}
+      `('$htmlString does not equal $templateString', ({ htmlString, templateString }) => {
+        expect(htmlString).not.toMatchInterpolatedText(templateString);
+      });
+    });
+  });
+});