Caesar cipher [Fixed #40] [Fixed #44]

src/_Classics_/caesar_cipher/caesarCipher.test.js

@@ -0,0 +1,67 @@
+/* eslint-disable linebreak-style */
+/* eslint-disable no-else-return */
+const caesarCipher = require('./caeserCipher');
+
+describe('Caesar Cipher tests', () => {
+  it('Shift not passed', () => {
+    const ocString = 'Hello World';
+    const enCiphered = caesarCipher(ocString);
+    expect(ocString).toBe(enCiphered);
+  });
+
+  it('Encipher equals decipher', () => {
+    const ocString = 'Hello World';
+    const enCiphered = caesarCipher(ocString, 1);
+    const deCiphered = caesarCipher(enCiphered, -1);
+    expect(ocString).toBe(deCiphered);
+  });
+
+  it('Shift lower than string length works', () => {
+    const ocString = 'Hello World';
+    const enCiphered = caesarCipher(ocString, 1);
+    const idealResult = 'Ifmmp Xpsme';
+    expect(enCiphered).toBe(idealResult);
+  });
+
+  it('Shift Higher than string length works', () => {
+    const ocString = 'Hello World';
+    const enCiphered = caesarCipher(ocString, 63);
+    const idealResult = caesarCipher(ocString, 1);
+    expect(enCiphered).toBe(idealResult);
+  });
+
+  it('Negative shift Works', () => {
+    const ocString = 'Ifmmp Xpsme';
+    const enCiphered = caesarCipher(ocString, -1);
+    const idealResult = 'Hello World';
+    expect(enCiphered).toBe(idealResult);
+  });
+
+  it('Shift is a numerical string', () => {
+    const ocString = 'Hello World';
+    const enCiphered = caesarCipher(ocString, '1');
+    const idealResult = 'Ifmmp Xpsme';
+    expect(enCiphered).toBe(idealResult);
+  });
+
+  it('Shift is not a numbered string', () => {
+    function test() {
+      caesarCipher('Hello World', 'abc');
+    }
+    expect(test).toThrow('Invalid Shift Provided');
+  });
+
+  it('toEncipher is NaN', () => {
+    function test() {
+      caesarCipher(NaN, 1);
+    }
+    expect(test).toThrowError('Invalid string provided');
+  });
+
+  it('toEncipher is undefined', () => {
+    function test() {
+      caesarCipher(undefined, 1);
+    }
+    expect(test).toThrowError('Invalid string provided');
+  });
+});

src/_Classics_/caesar_cipher/caeserCipher.js

@@ -0,0 +1,46 @@
+/**
+ * Most simplest encryption scheme. Read more: [http://practicalcryptography.com/ciphers/caesar-cipher/]
+ **/
+function caesarCipher(toEncipher, shift = 0) {
+  // If required for very strict shift checking then remove '=0'
+  if (Number.isNaN(Number(shift)) === true) {
+    throw new Error('Invalid Shift Provided');
+  } else {
+    shift = parseInt(Number(shift), 10);
+  }
+
+  if (typeof (toEncipher) === 'string' || (typeof (toEncipher) === 'number' && Number.isNaN(toEncipher) === false)) {
+    toEncipher = String(toEncipher);
+  } else {
+    throw new Error('Invalid string provided');
+  }
+
+  // These are the valid entries aacepted, you can change it according to requirements
+  const validEntries = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
+
+  shift %= validEntries.length;
+
+  let output = '';
+  for (const char of toEncipher) {
+    if (char === ' ') {
+      output += ' ';
+      continue;
+      // ------- If you donot want to accept invalid entries then uncomment below block
+    /*
+    ========================================================================================================
+            } else if (validEntries.indexOf(char) === -1) {return Error ('invalid character' + char)}
+    ========================================================================================================
+    and comment out the below block
+    */
+      //= ======================================================================================================
+    } else if (validEntries.indexOf(char) === -1) {
+      output += char;
+      continue;
+    }
+    //= ======================================================================================================
+    output += (validEntries.indexOf(char) + shift <= validEntries.length) ? validEntries[validEntries.indexOf(char) + shift] : validEntries[(validEntries.indexOf(char) + shift) % validEntries.length];
+  }
+  return output;
+}
+
+module.exports = caesarCipher;