diff --git a/js/src/util/subscribe-to-events.spec.js b/js/src/util/subscribe-to-events.spec.js
new file mode 100644
index 000000000..3629e8d79
--- /dev/null
+++ b/js/src/util/subscribe-to-events.spec.js
@@ -0,0 +1,115 @@
+// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+import { spy, stub } from 'sinon';
+
+import subscribeToEvents from './subscribe-to-events';
+import {
+  pastLogs, liveLogs, createApi, createContract
+} from './subscribe-to-events.test.js';
+
+const delay = (t) => new Promise((resolve) => {
+  setTimeout(resolve, t);
+});
+
+describe('util/subscribe-to-events', () => {
+  beforeEach(function () {
+    this.api = createApi();
+    this.contract = createContract(this.api);
+  });
+
+  it('installs a filter', async function () {
+    const { api, contract } = this;
+
+    subscribeToEvents(contract, [ 'Foo', 'Bar' ]);
+    await delay(0);
+
+    expect(api.eth.newFilter.calledOnce).to.equal(true);
+    expect(api.eth.newFilter.firstCall.args).to.eql([ {
+      fromBlock: 0, toBlock: 'latest',
+      address: contract.address,
+      topics: [ [
+        contract.instance.Foo.signature,
+        contract.instance.Bar.signature
+      ] ]
+    } ]);
+  });
+
+  it('queries & parses logs in the beginning', async function () {
+    const { api, contract } = this;
+
+    subscribeToEvents(contract, [ 'Foo', 'Bar' ]);
+
+    await delay(0);
+    expect(api.eth.getFilterLogs.callCount).to.equal(1);
+    expect(api.eth.getFilterLogs.firstCall.args).to.eql([ 123 ]);
+
+    await delay(0);
+    expect(contract.parseEventLogs.callCount).to.equal(1);
+  });
+
+  it('emits logs in the beginning', async function () {
+    const { contract } = this;
+
+    const onLog = spy();
+    const onFoo = spy();
+    const onBar = spy();
+    subscribeToEvents(contract, [ 'Foo', 'Bar' ])
+      .on('log', onLog)
+      .on('Foo', onFoo)
+      .on('Bar', onBar);
+
+    await delay(0);
+
+    expect(onLog.callCount).to.equal(2);
+    expect(onLog.firstCall.args).to.eql([ pastLogs[0] ]);
+    expect(onLog.secondCall.args).to.eql([ pastLogs[1] ]);
+    expect(onFoo.callCount).to.equal(1);
+    expect(onFoo.firstCall.args).to.eql([ pastLogs[0] ]);
+    expect(onBar.callCount).to.equal(1);
+    expect(onBar.firstCall.args).to.eql([ pastLogs[1] ]);
+  });
+
+  it('uninstalls the filter on sunsubscribe', async function () {
+    const { api, contract } = this;
+
+    const s = subscribeToEvents(contract, [ 'Foo', 'Bar' ]);
+    await delay(0);
+    s.unsubscribe();
+    await delay(0);
+
+    expect(api.eth.uninstallFilter.calledOnce).to.equal(true);
+    expect(api.eth.uninstallFilter.firstCall.args).to.eql([ 123 ]);
+  });
+
+  it('checks for new events regularly', async function () {
+    const { api, contract } = this;
+    api.eth.getFilterLogs = stub().resolves([]);
+
+    const onLog = spy();
+    const onBar = spy();
+    const s = subscribeToEvents(contract, [ 'Bar' ], { interval: 5 })
+      .on('log', onLog)
+      .on('Bar', onBar);
+    await delay(9);
+    s.unsubscribe();
+
+    expect(onLog.callCount).to.equal(1);
+    expect(onLog.firstCall.args).to.eql([ liveLogs[0] ]);
+    expect(onBar.callCount).to.equal(1);
+    expect(onBar.firstCall.args).to.eql([ liveLogs[0] ]);
+  });
+});
diff --git a/js/src/util/subscribe-to-events.test.js b/js/src/util/subscribe-to-events.test.js
new file mode 100644
index 000000000..642f8e592
--- /dev/null
+++ b/js/src/util/subscribe-to-events.test.js
@@ -0,0 +1,53 @@
+// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+import { stub } from 'sinon';
+
+export const ADDRESS = '0x1111111111111111111111111111111111111111';
+
+export const pastLogs = [
+  { event: 'Foo', type: 'mined', address: ADDRESS, params: {} },
+  { event: 'Bar', type: 'mined', address: ADDRESS, params: {} }
+];
+
+export const liveLogs = [
+  { event: 'Bar', type: 'mined', address: ADDRESS, params: { foo: 'bar' } }
+];
+
+export const createApi = () => ({
+  eth: {
+    newFilter: stub().resolves(123),
+    uninstallFilter: stub()
+      .rejects(new Error('unknown filter id'))
+      .withArgs(123).resolves(null),
+    getFilterLogs: stub()
+      .rejects(new Error('unknown filter id'))
+      .withArgs(123).resolves(pastLogs),
+    getFilterChanges: stub()
+      .rejects(new Error('unknown filter id'))
+      .withArgs(123).resolves(liveLogs)
+  }
+});
+
+export const createContract = (api) => ({
+  api,
+  address: ADDRESS,
+  instance: {
+    Foo: { signature: 'Foo signature' },
+    Bar: { signature: 'Bar signature' }
+  },
+  parseEventLogs: stub().returnsArg(0)
+});