Solution

src/validateEmail.test.js

@@ -8,7 +8,9 @@ describe(`Function 'validateEmail':`, () => {
   });
 
   it(`should return boolean`, () => {
+    const result = validateEmail('');
 
+    expect(typeof result).toBe('boolean');
   });
 
   it(`should return 'true' for the valid email`, () => {
@@ -17,4 +19,29 @@ describe(`Function 'validateEmail':`, () => {
   });
 
   // write more tests here
+  it(`should return 'false' for the invalid email`, () => {
+    expect(validateEmail('')).toBeFalsy();
+  });
+
+  it(`should return 'false' for the invalid email that
+  contains not allowed chars
+  ! $ % & ' * + / = ? ^ { | } ~ :
+  `, () => {
+    expect(validateEmail('[email protected]')).toBeFalsy();
+  });
+
+  it(`should return 'false' if in domain part is not '@' char
+  `, () => {
+    expect(validateEmail('test838gmail.com')).toBeFalsy();
+  });
+
+  it(`should return 'false' if in domain part
+  is not include dot char`, () => {
+    expect(validateEmail('test838@gmailcom')).toBeFalsy();
+  });
+
+  it(`should return 'false' if in dots are at the beginning
+  or at the end of the string`, () => {
+    expect(validateEmail('[email protected].')).toBeFalsy();
+  });
 });