Solution

src/validateEmail.test.js

@@ -3,18 +3,45 @@
 describe(`Function 'validateEmail':`, () => {
   const validateEmail = require('./validateEmail');
 
-  it(`should be declared`, () => {
-    expect(validateEmail).toBeInstanceOf(Function);
-  });
+  it(`should be declared`, () => expect(validateEmail).toBeDefined());
 
   it(`should return boolean`, () => {
-
+    expect(typeof validateEmail('')).toBe('boolean');
   });
 
   it(`should return 'true' for the valid email`, () => {
-    expect(validateEmail('[email protected].'))
-      .toBeTruthy();
+    expect(validateEmail('[email protected]')).toBeTruthy();
+  });
+
+  it(`should return 'true' for email name containing digits only`, () => {
+    expect(validateEmail('[email protected]')).toBeTruthy();
+  });
+
+  it(`should return 'true' for email containing '-', '_' or '.'`, () => {
+    expect(validateEmail('[email protected]')).toBeTruthy();
+  });
+
+  it(`should return 'false' for email with cyrillic letters`, () => {
+    expect(validateEmail('моя_пошта@gmail.com')).toBeFalsy();
   });
 
-  // write more tests here
+  it(`should return 'false' for email beginning with '.'`, () => {
+    expect(validateEmail('[email protected]')).toBeFalsy();
+  });
+
+  it(`should return 'false' for domain beginning with '.'`, () => {
+    expect(validateEmail('[email protected]')).toBeFalsy();
+  });
+
+  it(`should return 'false' for email containing not allowed chars`, () => {
+    const notAllowedChars = `!$%&'*+/=?^{|}~`.split('');
+
+    notAllowedChars.forEach((char) => {
+      expect(validateEmail(`my${char}[email protected]`)).toBeFalsy();
+    });
+  });
+
+  it(`should return 'false' for email without '@'`, () => {
+    expect(validateEmail('my_e-mail_gmail.com')).toBeFalsy();
+  });
 });