diff --git a/test/spec/modules/yandexIdSystem_spec.js b/test/spec/modules/yandexIdSystem_spec.js
new file mode 100644
index 00000000000..bd798f3a3f2
--- /dev/null
+++ b/test/spec/modules/yandexIdSystem_spec.js
@@ -0,0 +1,155 @@
+import { yandexIdSubmodule, storage } from '../../../modules/yandexIdSystem.js';
+
+const MIN_METRICA_ID_LEN = 17;
+
+/**
+ * @typedef {import('sinon').SinonStub} SinonStub
+ * @typedef {import('sinon').SinonSandbox} SinonSandbox
+ */
+
+describe('YandexId module', () => {
+  /** @type {SinonSandbox} */
+  let sandbox;
+  /** @type {SinonStub} */
+  let setCookieStub;
+  /** @type {SinonStub} */
+  let getCookieStub;
+  /** @type {SinonStub} */
+  let getLocalStorageStub;
+  /** @type {SinonStub} */
+  let setLocalStorageStub;
+  /** @type {SinonStub} */
+  let cookiesAreEnabledStub;
+  /** @type {SinonStub} */
+  let getCryptoRandomValuesStub;
+  /** @type {SinonStub} */
+  let randomStub;
+
+  beforeEach(() => {
+    sandbox = sinon.sandbox.create();
+    getCookieStub = sandbox.stub(storage, 'getCookie');
+    setCookieStub = sandbox.stub(storage, 'setCookie');
+    getLocalStorageStub = sandbox.stub(storage, 'getDataFromLocalStorage');
+    setLocalStorageStub = sandbox.stub(storage, 'setDataInLocalStorage');
+    cookiesAreEnabledStub = sandbox.stub(storage, 'cookiesAreEnabled');
+    cookiesAreEnabledStub.returns(true);
+
+    getCryptoRandomValuesStub = sandbox
+      .stub(window.crypto, 'getRandomValues')
+      .callsFake((bufferView) => {
+        bufferView[0] = 10000;
+      });
+    randomStub = sandbox.stub(window.Math, 'random').returns(0.555);
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+  });
+
+  describe('getId()', () => {
+    describe('user id format', () => {
+      it('matches Yandex Metrica format', () => {
+        const generatedId = yandexIdSubmodule.getId().id;
+        expect(isNaN(generatedId)).to.be.false;
+        expect(generatedId).to.have.length.greaterThanOrEqual(
+          MIN_METRICA_ID_LEN
+        );
+      });
+    });
+
+    describe('when user id is set', () => {
+      const dummyId = Array(MIN_METRICA_ID_LEN).fill(1).join('');
+
+      beforeEach(() => {
+        getCookieStub.returns(dummyId);
+      });
+
+      it('returns id', () => {
+        const { id } = yandexIdSubmodule.getId();
+
+        expect(id).to.equal(dummyId);
+      });
+
+      it('does not change existing id', () => {
+        yandexIdSubmodule.getId();
+
+        expect(setCookieStub.lastCall.args[1]).to.equal(dummyId);
+      });
+    });
+
+    describe('when user id is not set', () => {
+      beforeEach(() => {
+        getCookieStub.returns(undefined);
+      });
+
+      it('returns id', () => {
+        const id = yandexIdSubmodule.getId();
+
+        expect(id).not.to.be.undefined;
+      });
+
+      it('sets id', () => {
+        yandexIdSubmodule.getId()
+
+        expect(setCookieStub.calledOnce).to.be.true;
+      });
+    });
+
+    describe('storage interaction', () => {
+      describe('when cookie storage is disabled', () => {
+        it('should not use storage api', () => {
+          cookiesAreEnabledStub.returns(false);
+
+          yandexIdSubmodule.getId();
+
+          expect(cookiesAreEnabledStub.called).to.be.true;
+          expect(getCookieStub.called).to.be.false;
+          expect(setCookieStub.called).to.be.false;
+          expect(getLocalStorageStub.called).to.be.false;
+          expect(setLocalStorageStub.called).to.be.false;
+        });
+      });
+
+      it('should use cookie', () => {
+        yandexIdSubmodule.getId();
+
+        expect(cookiesAreEnabledStub.called).to.be.true;
+        expect(getCookieStub.calledOnce).to.be.true;
+        expect(setCookieStub.calledOnce).to.be.true;
+      });
+
+      it('should not use localStorage', () => {
+        yandexIdSubmodule.getId();
+
+        expect(getLocalStorageStub.called).to.be.false;
+        expect(setLocalStorageStub.called).to.be.false;
+      });
+    });
+
+    describe('crypto', () => {
+      it('uses Math.random when crypto is not available', () => {
+        sandbox.stub(window, 'crypto').value(undefined);
+
+        yandexIdSubmodule.getId();
+
+        expect(randomStub.calledOnce).to.be.true;
+        expect(getCryptoRandomValuesStub.called).to.be.false;
+      });
+
+      it('uses crypto when it is available', () => {
+        yandexIdSubmodule.getId();
+
+        expect(randomStub.called).to.be.false;
+        expect(getCryptoRandomValuesStub.calledOnce).to.be.true;
+      });
+    });
+  });
+
+  describe('decode()', () => {
+    it('should not transform value', () => {
+      const value = 'test value';
+
+      expect(yandexIdSubmodule.decode(value).yandexId).to.equal(value);
+    });
+  });
+});