Improve pwd creation code and unit testing

src/index.ts

@@ -16,16 +16,8 @@ export class Sesame {
    */
   public static create(length: number): string {
     const availableChars = Sesame.AVAILABLE_CHARS;
-    const randomChars = new Array(length);
     const cryptoArray = new Uint32Array(length);
-
     crypto.getRandomValues(cryptoArray);
-
-    for (let i = 0; i < length; i++) {
-      const randomIndex = cryptoArray[i] % availableChars.length;
-      randomChars[i] = availableChars.charAt(randomIndex);
-    }
-
-    return randomChars.join('');
+    return Array.from(cryptoArray, num => availableChars.charAt(num % availableChars.length)).join('');
   }
 }

test/index.test.ts

@@ -12,4 +12,33 @@ describe('Sesame', () => {
     // Then
     expect(password.length).toEqual(expectedLength);
   });
+
+  it('should return a string of the specified length', () => {
+    // Given a specified length
+    const length = 10;
+    // When the password is created
+    const password = Sesame.create(length);
+    // Then the password should have the specified length
+    expect(password).to.have.lengthOf(length);
+  });
+
+  it('should only contain characters from the available characters', () => {
+    // Given a password of length 100
+    const password = Sesame.create(100);
+    const availableChars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*{}(),.;:/<>?|_-+=';
+    // When we check each character in the password
+    for (const char of password) {
+      // Then each character should be in the list of available characters
+      expect(availableChars).to.include(char);
+    }
+  });
+
+  it('should generate different passwords each time', () => {
+    // Given two passwords of equal length
+    const password1 = Sesame.create(10);
+    const password2 = Sesame.create(10);
+    // When we compare the two passwords
+    // Then they should not be equal
+    expect(password1).to.not.equal(password2);
+  });
 });