diff --git a/lib/core/Cetra.test.js b/lib/core/Cetra.test.js
new file mode 100644
index 0000000..98210d8
--- /dev/null
+++ b/lib/core/Cetra.test.js
@@ -0,0 +1,76 @@
+import Cetra from './Cetra';
+
+describe('Cetra', () => {
+	let cetra;
+
+	beforeEach(() => {
+		cetra = new Cetra();
+	});
+
+	afterEach(() => {
+		cetra = null;
+	});
+
+	describe('general', () => {
+		it('should emit the onAfterInit event', () => {
+			const spy = jest.fn();
+			let _test = new Cetra(new Map([['onAfterInit', spy]]));
+			expect(spy).toHaveBeenCalled().withArgs('onAfterInit');
+		});
+	});
+
+	describe('uid', () => {
+		it('should generate a unique identifier', () => {
+			const identifier = cetra.uid();
+
+			expect(typeof identifier).toBe('string');
+			expect(identifier.length).toBeGreaterThan(0);
+		});
+
+		it('should generate a unique identifier with the specified number of groups and group length', () => {
+			const numGroups = 3;
+			const groupLength = 4;
+
+			const identifier = cetra.uid(numGroups, groupLength);
+
+			const groups = identifier.split('-');
+			expect(groups.length).toBe(numGroups);
+			groups.forEach((group) => {
+				expect(group.length).toBe(groupLength);
+			});
+		});
+	});
+
+	describe('isUrl', () => {
+		it('should return true for a valid url', () => {
+			const url = 'https://www.google.com';
+
+			expect(cetra.isUrl(url)).toBe(true);
+		});
+
+		it('should return false for an invalid url', () => {
+			const url = 'https://www.google';
+
+			expect(cetra.isUrl(url)).toBe(false);
+		});
+
+		it('should return false for a non-string', () => {
+			const url = 123;
+
+			expect(cetra.isUrl(url)).toBe(false);
+		});
+
+		it('should return false for an empty string', () => {
+			const url = '';
+
+			expect(cetra.isUrl(url)).toBe(false);
+		});
+
+		it('should return true for a relative path', () => {
+			const url = '/test';
+
+			expect(cetra.isUrl(url)).toBe(true);
+		});
+	});
+});
+import Cetra from './Cetra';