diff --git a/src/checkPassword.js b/src/checkPassword.js
index 1a6fc05..fd65419 100644
--- a/src/checkPassword.js
+++ b/src/checkPassword.js
@@ -8,10 +8,11 @@
 function checkPassword(password) {
   // eslint-disable-next-line
   const validPasswordRegex = /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[^a-zA-Z0-9])(?!.*\s).{8,16}$/;
-  const cyrillicValidation = /^((?![А-Яа-я]).)*$/;
+  const doHaveOtherLetters = password.match(/[a-z]/ig).length
+    !== password.match(/\p{Letter}/uig).length;
 
   // eslint-disable-next-line
-  if (password.match(validPasswordRegex) && password.match(cyrillicValidation)) {
+  if (password.match(validPasswordRegex) && !doHaveOtherLetters) {
     return true;
   }
 
diff --git a/src/checkPassword.test.js b/src/checkPassword.test.js
index 1e77e16..6acb0ee 100644
--- a/src/checkPassword.test.js
+++ b/src/checkPassword.test.js
@@ -2,18 +2,111 @@
 
 describe(`Function 'checkPassword':`, () => {
   const checkPassword = require('./checkPassword');
+  const generatePassword = (amountOfCharacters, partWithRequiredCharacters) => {
+    const different = amountOfCharacters - partWithRequiredCharacters.length;
+
+    if (different <= 0) {
+      return partWithRequiredCharacters.slice(0, amountOfCharacters);
+    }
+
+    const randomLetterASCII = (howManyTimes) => {
+      let generatedLetters = '';
+
+      for (let i = 1; i <= howManyTimes; i++) {
+        const codeASCII = Math.floor(Math.random() * 26) + 97;
+
+        generatedLetters += String.fromCharCode(codeASCII);
+      }
+
+      return generatedLetters;
+    };
+
+    const randomPart = randomLetterASCII(amountOfCharacters
+      - partWithRequiredCharacters.length);
+    const result = partWithRequiredCharacters + randomPart;
+
+    return result;
+  };
 
   it(`should be declared`, () => {
     expect(checkPassword).toBeInstanceOf(Function);
   });
 
   it(`should return boolean`, () => {
+    const typeOfValue = typeof checkPassword('B34ji^sska');
 
+    expect(typeOfValue).toBeTruthy();
   });
 
   it(`should return 'true' for the valid password with 8 characters`, () => {
+    const value = generatePassword(8, '1^B');
 
+    expect(checkPassword(value)).toBe(true);
   });
 
-  // write more tests here
+  it(`should return 'true' for the valid password with 9 characters`, () => {
+    const value = generatePassword(9, '1^B');
+
+    expect(checkPassword(value)).toBe(true);
+  });
+
+  it(`should return 'true' for the valid password with 15 characters`, () => {
+    const value = generatePassword(15, '1^B');
+
+    expect(checkPassword(value)).toBe(true);
+  });
+
+  it(`should return 'true' for the valid password with 16 characters`, () => {
+    const value = generatePassword(16, '1^B');
+
+    expect(checkPassword(value)).toBe(true);
+  });
+
+  it(`should return 'false' for the valid password with 7 characters`, () => {
+    const value = generatePassword(7, '1^B');
+
+    expect(checkPassword(value)).toBe(false);
+  });
+
+  it(`should return 'false' for the valid password with 17 characters`, () => {
+    const value = generatePassword(17, '1^B');
+
+    expect(checkPassword(value)).toBe(false);
+  });
+
+  it(`should return 'false' if `
+      + `password doesn't contain any digit`, () => {
+    const value = generatePassword(10, '^B');
+
+    expect(checkPassword(value)).toBe(false);
+  });
+
+  it(`should return 'false' if `
+      + `password doesn't contain any special character`, () => {
+    const value = generatePassword(10, '1B');
+
+    expect(checkPassword(value)).toBe(false);
+  });
+
+  it(`should return 'false' if `
+      + `password doesn't contain any upperCase`, () => {
+    const value = generatePassword(10, '1^');
+
+    expect(checkPassword(value)).toBe(false);
+  });
+
+  it(`should return 'false' if `
+      + `password contains non-Latin alphabet`, () => {
+    const value = [
+      generatePassword(10, '1^BaŁ]\\'),
+      generatePassword(10, '1^Baџ]\\'),
+      generatePassword(10, '1^Baó]\\'),
+      generatePassword(10, '1^Baä]\\'),
+    ];
+
+    value.forEach((password, i) => {
+      expect(checkPassword(password))
+        .toBe(false);
+    });
+  });
 });