diff --git a/src/packages/core/utils/state-manager/state.manager.test.ts b/src/packages/core/utils/state-manager/state.manager.test.ts
new file mode 100644
index 0000000000..5f86281b33
--- /dev/null
+++ b/src/packages/core/utils/state-manager/state.manager.test.ts
@@ -0,0 +1,141 @@
+import { UmbStateManager } from './state.manager.js';
+import { expect } from '@open-wc/testing';
+import { Observable } from '@umbraco-cms/backoffice/external/rxjs';
+import { customElement } from '@umbraco-cms/backoffice/external/lit';
+import { UmbControllerHostElementMixin } from '@umbraco-cms/backoffice/controller-api';
+
+@customElement('test-my-controller-host')
+class UmbTestControllerHostElement extends UmbControllerHostElementMixin(HTMLElement) {}
+
+describe('UmbSelectionManager', () => {
+	let manager: UmbStateManager;
+	const state1 = { unique: '1', message: 'State 1' };
+	const state2 = { unique: '2', message: 'State 2' };
+
+	beforeEach(() => {
+		const hostElement = new UmbTestControllerHostElement();
+		manager = new UmbStateManager(hostElement);
+	});
+
+	describe('Public API', () => {
+		describe('properties', () => {
+			it('has a states property', () => {
+				expect(manager).to.have.property('states').to.be.an.instanceOf(Observable);
+			});
+
+			it('has a isOn property', () => {
+				expect(manager).to.have.property('isOn').to.be.an.instanceOf(Observable);
+			});
+
+			it('has a isOff property', () => {
+				expect(manager).to.have.property('isOff').to.be.an.instanceOf(Observable);
+			});
+		});
+
+		describe('methods', () => {
+			it('has a addState method', () => {
+				expect(manager).to.have.property('addState').that.is.a('function');
+			});
+
+			it('has a addStates method', () => {
+				expect(manager).to.have.property('addStates').that.is.a('function');
+			});
+
+			it('has a removeState method', () => {
+				expect(manager).to.have.property('removeState').that.is.a('function');
+			});
+
+			it('has a getStates method', () => {
+				expect(manager).to.have.property('getStates').that.is.a('function');
+			});
+
+			it('has a clear method', () => {
+				expect(manager).to.have.property('clear').that.is.a('function');
+			});
+		});
+	});
+
+	describe('Add State', () => {
+		it('throws an error if the state does not have a unique property', () => {
+			// @ts-ignore - Testing invalid input
+			expect(() => manager.addState({ message: 'State 1' })).to.throw();
+		});
+
+		it('adds a single state to the states array', () => {
+			manager.addState(state1);
+			expect(manager.getStates()).to.deep.equal([state1]);
+		});
+
+		it('adds multiple states to the states array', () => {
+			manager.addStates([state1, state2]);
+			expect(manager.getStates()).to.deep.equal([state1, state2]);
+		});
+
+		it('updates the observable', (done) => {
+			manager.addState(state1);
+
+			manager.states
+				.subscribe((value) => {
+					expect(value[0]).to.equal(state1);
+					done();
+				})
+				.unsubscribe();
+		});
+	});
+
+	describe('Remove State', () => {
+		beforeEach(() => {
+			manager.addStates([state1, state2]);
+		});
+
+		it('removes a single state from the states array', () => {
+			manager.removeState('1');
+			expect(manager.getStates()).to.deep.equal([state2]);
+		});
+
+		it('removes multiple states from the states array', () => {
+			manager.removeStates(['1', '2']);
+			expect(manager.getStates()).to.deep.equal([]);
+		});
+
+		it('updates the observable', (done) => {
+			manager.removeState('1');
+
+			manager.states
+				.subscribe((value) => {
+					expect(value).to.deep.equal([state2]);
+					done();
+				})
+				.unsubscribe();
+		});
+	});
+
+	describe('Get States', () => {
+		it('returns all states', () => {
+			manager.addStates([state1, state2]);
+			expect(manager.getStates()).to.deep.equal([state1, state2]);
+		});
+	});
+
+	describe('Clear', () => {
+		beforeEach(() => {
+			manager.addStates([state1, state2]);
+		});
+
+		it('clears all states', () => {
+			manager.clear();
+			expect(manager.getStates()).to.deep.equal([]);
+		});
+
+		it('updates the observable', (done) => {
+			manager.clear();
+
+			manager.states
+				.subscribe((value) => {
+					expect(value).to.deep.equal([]);
+					done();
+				})
+				.unsubscribe();
+		});
+	});
+});