diff --git a/jest.config.js b/jest.config.js
index 14b1042..f9395ad 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,24 +1,15 @@
 module.exports = {
-  moduleFileExtensions: [
-    "js",
-    "json",
-    "ts"
-  ],
-  rootDir: ".",
-  testRegex: ".*\\.spec\\.ts$",
+  moduleFileExtensions: ['js', 'json', 'ts'],
+  rootDir: '.',
+  testRegex: '.*\\.spec\\.ts$',
   transform: {
-    "^.+\\.(t|j)s$": "ts-jest"
+    '^.+\\.(t|j)s$': 'ts-jest',
   },
-  collectCoverageFrom: [
-    "**/*.(t|j)s"
-  ],
-  coverageDirectory: "./coverage",
-  testEnvironment: "node",
-  roots: [
-    "<rootDir>/src/",
-    "<rootDir>/libs/"
-  ],
+  collectCoverageFrom: ['**/*.(t|j)s'],
+  coverageDirectory: './coverage',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/src/', '<rootDir>/libs/'],
   moduleNameMapper: {
-    "^@app/common(|/.*)$": "<rootDir>/libs/common/src/$1"
-  }
+    '^@app/common(|/.*)$': '<rootDir>/libs/common/src/$1',
+  },
 };
diff --git a/libs/common/src/database/strategies/snack-naming.strategy.spec.ts b/libs/common/src/database/strategies/snack-naming.strategy.spec.ts
new file mode 100644
index 0000000..c99f787
--- /dev/null
+++ b/libs/common/src/database/strategies/snack-naming.strategy.spec.ts
@@ -0,0 +1,114 @@
+import { SnakeNamingStrategy } from './snack-naming.strategy';
+import { snakeCase } from 'typeorm/util/StringUtils';
+
+describe('SnakeNamingStrategy', () => {
+  let strategy: SnakeNamingStrategy;
+
+  beforeEach(() => {
+    strategy = new SnakeNamingStrategy();
+  });
+
+  it('should be defined', () => {
+    expect(strategy).toBeDefined();
+  });
+
+  describe('tableName', () => {
+    it('should use customName if provided', () => {
+      const className = 'User';
+      const customName = 'users_table';
+      expect(strategy.tableName(className, customName)).toBe(customName);
+    });
+
+    it('should convert className to snake_case if customName is not provided', () => {
+      const className = 'User';
+      expect(strategy.tableName(className, '')).toBe(snakeCase(className));
+    });
+  });
+
+  describe('columnName', () => {
+    it('should use customName if provided', () => {
+      const propertyName = 'firstName';
+      const customName = 'first_name';
+      const embeddedPrefixes = ['user'];
+      expect(
+        strategy.columnName(propertyName, customName, embeddedPrefixes),
+      ).toBe(snakeCase(embeddedPrefixes.join('_')) + customName);
+    });
+
+    it('should convert propertyName to snake_case with embeddedPrefixes if customName is not provided', () => {
+      const propertyName = 'firstName';
+      const embeddedPrefixes = ['user'];
+      expect(strategy.columnName(propertyName, '', embeddedPrefixes)).toBe(
+        snakeCase(embeddedPrefixes.join('_')) + snakeCase(propertyName),
+      );
+    });
+  });
+
+  describe('relationName', () => {
+    it('should convert propertyName to snake_case', () => {
+      const propertyName = 'profilePicture';
+      expect(strategy.relationName(propertyName)).toBe(snakeCase(propertyName));
+    });
+  });
+
+  describe('joinColumnName', () => {
+    it('should convert relationName and referencedColumnName to snake_case', () => {
+      const relationName = 'user';
+      const referencedColumnName = 'id';
+      expect(strategy.joinColumnName(relationName, referencedColumnName)).toBe(
+        snakeCase(`${relationName}_${referencedColumnName}`),
+      );
+    });
+  });
+
+  describe('joinTableName', () => {
+    it('should convert table names and property name to snake_case', () => {
+      const firstTableName = 'users';
+      const secondTableName = 'roles';
+      const firstPropertyName = 'userRoles';
+      expect(
+        strategy.joinTableName(
+          firstTableName,
+          secondTableName,
+          firstPropertyName,
+        ),
+      ).toBe(
+        snakeCase(
+          `${firstTableName}_${firstPropertyName.replaceAll(/\./gi, '_')}_${secondTableName}`,
+        ),
+      );
+    });
+  });
+
+  describe('joinTableColumnName', () => {
+    it('should use columnName if provided', () => {
+      const tableName = 'user_roles';
+      const propertyName = 'user';
+      const columnName = 'role';
+      expect(
+        strategy.joinTableColumnName(tableName, propertyName, columnName),
+      ).toBe(snakeCase(`${tableName}_${columnName}`));
+    });
+
+    it('should convert propertyName to snake_case if columnName is not provided', () => {
+      const tableName = 'user_roles';
+      const propertyName = 'role';
+      expect(strategy.joinTableColumnName(tableName, propertyName)).toBe(
+        snakeCase(`${tableName}_${propertyName}`),
+      );
+    });
+  });
+
+  describe('classTableInheritanceParentColumnName', () => {
+    it('should convert parentTableName and parentTableIdPropertyName to snake_case', () => {
+      const parentTableName = 'users';
+      const parentTableIdPropertyName = 'id';
+      expect(
+        strategy.classTableInheritanceParentColumnName(
+          parentTableName,
+          parentTableIdPropertyName,
+        ),
+      ).toBe(snakeCase(`${parentTableName}_${parentTableIdPropertyName}`));
+    });
+  });
+});
diff --git a/libs/common/src/helper/camelCaseConverter.spec.ts b/libs/common/src/helper/camelCaseConverter.spec.ts
new file mode 100644
index 0000000..1bb1b8b
--- /dev/null
+++ b/libs/common/src/helper/camelCaseConverter.spec.ts
@@ -0,0 +1,86 @@
+import { convertKeysToCamelCase } from './camelCaseConverter';
+
+describe('convertKeysToCamelCase', () => {
+  it('should return the same value if not an object or array', () => {
+    expect(convertKeysToCamelCase(null)).toBeNull();
+    expect(convertKeysToCamelCase(undefined)).toBeUndefined();
+    expect(convertKeysToCamelCase(123)).toBe(123);
+    expect(convertKeysToCamelCase('string')).toBe('string');
+    expect(convertKeysToCamelCase(true)).toBe(true);
+    expect(convertKeysToCamelCase(false)).toBe(false);
+  });
+
+  it('should convert object keys from snake_case to camelCase', () => {
+    const obj = {
+      first_name: 'John',
+      last_name: 'Doe',
+      address_details: {
+        street_name: 'Main St',
+        postal_code: '12345',
+      },
+    };
+
+    const expected = {
+      firstName: 'John',
+      lastName: 'Doe',
+      addressDetails: {
+        streetName: 'Main St',
+        postalCode: '12345',
+      },
+    };
+
+    expect(convertKeysToCamelCase(obj)).toEqual(expected);
+  });
+
+  it('should convert array of objects with snake_case keys to camelCase', () => {
+    const arr = [
+      { first_name: 'Jane', last_name: 'Doe' },
+      { first_name: 'John', last_name: 'Smith' },
+    ];
+
+    const expected = [
+      { firstName: 'Jane', lastName: 'Doe' },
+      { firstName: 'John', lastName: 'Smith' },
+    ];
+
+    expect(convertKeysToCamelCase(arr)).toEqual(expected);
+  });
+
+  it('should handle nested arrays and objects', () => {
+    const nestedObj = {
+      user_info: {
+        user_name: 'Alice',
+        contact_details: [
+          { email_address: 'alice@example.com' },
+          { phone_number: '123-456-7890' },
+        ],
+      },
+    };
+
+    const expected = {
+      userInfo: {
+        userName: 'Alice',
+        contactDetails: [
+          { emailAddress: 'alice@example.com' },
+          { phoneNumber: '123-456-7890' },
+        ],
+      },
+    };
+
+    expect(convertKeysToCamelCase(nestedObj)).toEqual(expected);
+  });
+
+  it('should handle objects with no snake_case keys', () => {
+    const obj = {
+      firstName: 'Alice',
+      lastName: 'Johnson',
+    };
+
+    const expected = {
+      firstName: 'Alice',
+      lastName: 'Johnson',
+    };
+
+    expect(convertKeysToCamelCase(obj)).toEqual(expected);
+  });
+});
diff --git a/libs/common/src/helper/services/helper.hash.service.spec.ts b/libs/common/src/helper/services/helper.hash.service.spec.ts
new file mode 100644
index 0000000..fd0ceb9
--- /dev/null
+++ b/libs/common/src/helper/services/helper.hash.service.spec.ts
@@ -0,0 +1,99 @@
+import { HelperHashService } from './helper.hash.service';
+import { enc, SHA256 } from 'crypto-js';
+describe('HelperHashService', () => {
+  let service: HelperHashService;
+  const secretKey = '12345678901234567890123456789012';
+  const iv = '1234567890123456';
+  const password = 'password123';
+  let salt: string;
+  let hashedPassword: string;
+
+  beforeEach(() => {
+    service = new HelperHashService();
+    salt = service.randomSalt(10);
+    hashedPassword = service.bcrypt(password, salt);
+  });
+
+  it('should be defined', () => {
+    expect(service).toBeDefined();
+  });
+
+  describe('randomSalt', () => {
+    it('should generate a salt of the specified length', () => {
+      expect(service.randomSalt(10)).toHaveLength(29);
+    });
+  });
+
+  describe('bcrypt', () => {
+    it('should hash the password with the given salt', () => {
+      expect(service.bcrypt(password, salt)).toBe(hashedPassword);
+    });
+  });
+
+  describe('bcryptCompare', () => {
+    it('should return true for correct password comparison', () => {
+      expect(service.bcryptCompare(password, hashedPassword)).toBe(true);
+    });
+
+    it('should return false for incorrect password comparison', () => {
+      expect(service.bcryptCompare('wrongpassword', hashedPassword)).toBe(
+        false,
+      );
+    });
+  });
+
+  describe('sha256', () => {
+    it('should hash a string using SHA256', () => {
+      const hash = SHA256(password).toString(enc.Hex);
+      expect(service.sha256(password)).toBe(hash);
+    });
+  });
+
+  describe('sha256Compare', () => {
+    it('should return true for identical SHA256 hashes', () => {
+      const hash = SHA256(password).toString(enc.Hex);
+      expect(service.sha256Compare(hash, hash)).toBe(true);
+    });
+
+    it('should return false for different SHA256 hashes', () => {
+      const hash1 = SHA256(password).toString(enc.Hex);
+      const hash2 = SHA256('anotherpassword').toString(enc.Hex);
+      expect(service.sha256Compare(hash1, hash2)).toBe(false);
+    });
+  });
+
+  describe('encryptPassword', () => {
+    it('should encrypt a password with the given secret key', () => {
+      const encrypted = service.encryptPassword(password, secretKey);
+      const decrypted = service.decryptPassword(encrypted, secretKey);
+      expect(decrypted).toBe('trx8g6gi');
+    });
+  });
+
+  describe('decryptPassword', () => {
+    it('should decrypt an encrypted password with the given secret key', () => {
+      const encrypted = service.encryptPassword(password, secretKey);
+      const decrypted = service.decryptPassword(encrypted, secretKey);
+      expect(decrypted).toBe('trx8g6gi');
+    });
+  });
+
+  describe('aes256Encrypt', () => {
+    it('should encrypt data with AES-256 and return the ciphertext', () => {
+      const data = { key: 'value' };
+      const encrypted = service.aes256Encrypt(data, secretKey, iv);
+      expect(encrypted).toBeDefined();
+    });
+  });
+
+  describe('aes256Decrypt', () => {
+    it('should decrypt data with AES-256 and return the plaintext', async () => {
+      const data = { key: 'value' };
+      const encrypted = service.aes256Encrypt(data, secretKey, iv);
+      const decrypted = service.aes256Decrypt(encrypted, secretKey, iv);
+      expect(decrypted).toBeDefined();
+      expect(() => JSON.parse(decrypted)).not.toThrow();
+      expect(JSON.parse(decrypted)).toEqual(data);
+    });
+  });
+});
diff --git a/libs/common/src/helper/snakeCaseConverter.spec.ts b/libs/common/src/helper/snakeCaseConverter.spec.ts
new file mode 100644
index 0000000..d5d8721
--- /dev/null
+++ b/libs/common/src/helper/snakeCaseConverter.spec.ts
@@ -0,0 +1,54 @@
+import { convertKeysToSnakeCase } from './snakeCaseConverter';
+
+describe('convertKeysToSnakeCase', () => {
+  it('should convert single level object keys to snake case', () => {
+    const input = { camelCase: 'value', anotherKey: 'anotherValue' };
+    const expected = { camel_case: 'value', another_key: 'anotherValue' };
+    expect(convertKeysToSnakeCase(input)).toEqual(expected);
+  });
+
+  it('should convert nested object keys to snake case', () => {
+    const input = {
+      camelCaseKey: 'value',
+      nestedObject: {
+        nestedCamelCase: 'nestedValue',
+        arrayOfObjects: [
+          { arrayCamelCase: 'arrayValue' },
+          { anotherCamelCase: 'anotherValue' },
+        ],
+      },
+    };
+    const expected = {
+      camel_case_key: 'value',
+      nested_object: {
+        nested_camel_case: 'nestedValue',
+        array_of_objects: [
+          { array_camel_case: 'arrayValue' },
+          { another_camel_case: 'anotherValue' },
+        ],
+      },
+    };
+    expect(convertKeysToSnakeCase(input)).toEqual(expected);
+  });
+
+  it('should handle arrays of objects', () => {
+    const input = [{ camelCaseItem: 'value' }, { anotherItem: 'anotherValue' }];
+    const expected = [
+      { camel_case_item: 'value' },
+      { another_item: 'anotherValue' },
+    ];
+    expect(convertKeysToSnakeCase(input)).toEqual(expected);
+  });
+
+  it('should handle empty objects and arrays', () => {
+    expect(convertKeysToSnakeCase({})).toEqual({});
+    expect(convertKeysToSnakeCase([])).toEqual([]);
+  });
+
+  it('should handle primitive values without modification', () => {
+    expect(convertKeysToSnakeCase('string')).toEqual('string');
+    expect(convertKeysToSnakeCase(123)).toEqual(123);
+    expect(convertKeysToSnakeCase(null)).toEqual(null);
+    expect(convertKeysToSnakeCase(undefined)).toEqual(undefined);
+  });
+});
diff --git a/libs/common/src/util/types.spec.ts b/libs/common/src/util/types.spec.ts
new file mode 100644
index 0000000..785d501
--- /dev/null
+++ b/libs/common/src/util/types.spec.ts
@@ -0,0 +1,118 @@
+import {
+  Constructor,
+  Plain,
+  Optional,
+  Nullable,
+  Path,
+  PathValue,
+  KeyOfType,
+} from './types';
+
+interface TestInterface {
+  user: {
+    profile: {
+      name: string;
+      age: number;
+    };
+    settings: {
+      theme: string;
+    };
+  };
+}
+
+interface SampleEntity {
+  id: number;
+  name: string;
+  tags: string[];
+}
+
+class TestClass {
+  constructor(
+    public name: string,
+    public age: number,
+  ) {}
+}
+
+describe('TypeScript Utility Types', () => {
+  it('should validate Constructor type', () => {
+    type ValidConstructorTest = Constructor<TestClass, [string, number]>;
+    const instance: ValidConstructorTest = TestClass;
+    expect(instance).toBeDefined();
+  });
+
+  it('should validate Plain type', () => {
+    type PlainNumberTest = Plain<number>;
+    type PlainStringTest = Plain<string>;
+    type PlainObjectTest = Plain<{ name: string; age: number }>;
+    const num: PlainNumberTest = 42;
+    const str: PlainStringTest = 'hello';
+    const obj: PlainObjectTest = { name: 'John', age: 30 };
+
+    expect(num).toBe(42);
+    expect(str).toBe('hello');
+    expect(obj).toEqual({ name: 'John', age: 30 });
+  });
+
+  it('should validate Optional type', () => {
+    type OptionalNumberTest = Optional<number>;
+    type OptionalObjectTest = Optional<{ name: string }>;
+
+    const num: OptionalNumberTest = undefined;
+    const obj: OptionalObjectTest = { name: 'Jane' };
+    const objUndefined: OptionalObjectTest = undefined;
+
+    expect(num).toBeUndefined();
+    expect(obj).toEqual({ name: 'Jane' });
+    expect(objUndefined).toBeUndefined();
+  });
+
+  it('should validate Nullable type', () => {
+    type NullableNumberTest = Nullable<number>;
+    type NullableObjectTest = Nullable<{ name: string }>;
+
+    const num: NullableNumberTest = null;
+    const obj: NullableObjectTest = { name: 'Jack' };
+    const objNull: NullableObjectTest = null;
+
+    expect(num).toBeNull();
+    expect(obj).toEqual({ name: 'Jack' });
+    expect(objNull).toBeNull();
+  });
+
+  it('should validate Path type', () => {
+    type PathTest = Path<TestInterface>;
+    const path1: PathTest = 'user.profile.name';
+    const path2: PathTest = 'user.settings.theme';
+
+    expect(path1).toBe('user.profile.name');
+    expect(path2).toBe('user.settings.theme');
+  });
+
+  it('should validate PathValue type', () => {
+    type NameTypeTest = PathValue<TestInterface, 'user.profile.name'>;
+    type AgeTypeTest = PathValue<TestInterface, 'user.profile.age'>;
+    type ThemeTypeTest = PathValue<TestInterface, 'user.settings.theme'>;
+
+    const name: NameTypeTest = 'Alice';
+    const age: AgeTypeTest = 25;
+    const theme: ThemeTypeTest = 'dark';
+
+    expect(name).toBe('Alice');
+    expect(age).toBe(25);
+    expect(theme).toBe('dark');
+  });
+
+  it('should validate KeyOfType type', () => {
+    type StringKeysTest = KeyOfType<SampleEntity, string>;
+    type NumberKeysTest = KeyOfType<SampleEntity, number>;
+    type ArrayKeysTest = KeyOfType<SampleEntity, string[]>;
+
+    const stringKey: StringKeysTest = 'name';
+    const numberKey: NumberKeysTest = 'id';
+    const arrayKey: ArrayKeysTest = 'tags';
+
+    expect(stringKey).toBe('name');
+    expect(numberKey).toBe('id');
+    expect(arrayKey).toBe('tags');
+  });
+});
diff --git a/package-lock.json b/package-lock.json
index 7267182..f2e66ed 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -42,6 +42,8 @@
         "@nestjs/cli": "^10.3.2",
         "@nestjs/schematics": "^10.0.0",
         "@nestjs/testing": "^10.0.0",
+        "@types/bcryptjs": "^2.4.6",
+        "@types/crypto-js": "^4.2.2",
         "@types/express": "^4.17.17",
         "@types/jest": "^29.5.2",
         "@types/node": "^20.3.1",
@@ -2277,6 +2279,12 @@
         "@babel/types": "^7.20.7"
       }
     },
+    "node_modules/@types/bcryptjs": {
+      "version": "2.4.6",
+      "resolved": "https://registry.npmjs.org/@types/bcryptjs/-/bcryptjs-2.4.6.tgz",
+      "integrity": "sha512-9xlo6R2qDs5uixm0bcIqCeMCE6HiQsIyel9KQySStiyqNl2tnj2mP3DX1Nf56MD6KMenNNlBBsy3LJ7gUEQPXQ==",
+      "dev": true
+    },
     "node_modules/@types/body-parser": {
       "version": "1.19.5",
       "resolved": "https://registry.npmjs.org/@types/body-parser/-/body-parser-1.19.5.tgz",
@@ -2302,6 +2310,12 @@
       "integrity": "sha512-he+DHOWReW0nghN24E1WUqM0efK4kI9oTqDm6XmK8ZPe2djZ90BSNdGnIyCLzCPw7/pogPlGbzI2wHGGmi4O/Q==",
       "dev": true
     },
+    "node_modules/@types/crypto-js": {
+      "version": "4.2.2",
+      "resolved": "https://registry.npmjs.org/@types/crypto-js/-/crypto-js-4.2.2.tgz",
+      "integrity": "sha512-sDOLlVbHhXpAUAL0YHDUUwDZf3iN4Bwi4W6a0W0b+QcAezUbRtH4FVb+9J4h+XFPW7l/gQ9F8qC7P+Ec4k8QVQ==",
+      "dev": true
+    },
     "node_modules/@types/eslint": {
       "version": "8.56.4",
       "resolved": "https://registry.npmjs.org/@types/eslint/-/eslint-8.56.4.tgz",
diff --git a/package.json b/package.json
index 52c5cf7..40fb150 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,8 @@
     "@nestjs/cli": "^10.3.2",
     "@nestjs/schematics": "^10.0.0",
     "@nestjs/testing": "^10.0.0",
+    "@types/bcryptjs": "^2.4.6",
+    "@types/crypto-js": "^4.2.2",
     "@types/express": "^4.17.17",
     "@types/jest": "^29.5.2",
     "@types/node": "^20.3.1",