diff --git a/src/lib/addons/__snapshots__/slack-app.test.ts.snap b/src/lib/addons/__snapshots__/slack-app.test.ts.snap
new file mode 100644
index 0000000000..796b0787f4
--- /dev/null
+++ b/src/lib/addons/__snapshots__/slack-app.test.ts.snap
@@ -0,0 +1,85 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Should not post to unexisting tagged channels 1`] = `
+{
+  "attachments": [
+    {
+      "actions": [
+        {
+          "name": "featureToggle",
+          "style": "primary",
+          "text": "Open in Unleash",
+          "type": "button",
+          "url": "http://some-url.com/projects/default/features/some-toggle",
+          "value": "featureToggle",
+        },
+      ],
+    },
+  ],
+  "channel": 2,
+  "text": "some@user.com *enabled* <http://some-url.com/projects/default/features/some-toggle|some-toggle> in *development* environment in project *default*",
+}
+`;
+
+exports[`Should post message when feature is toggled 1`] = `
+{
+  "attachments": [
+    {
+      "actions": [
+        {
+          "name": "featureToggle",
+          "style": "primary",
+          "text": "Open in Unleash",
+          "type": "button",
+          "url": "http://some-url.com/projects/default/features/some-toggle",
+          "value": "featureToggle",
+        },
+      ],
+    },
+  ],
+  "channel": 1,
+  "text": "some@user.com *enabled* <http://some-url.com/projects/default/features/some-toggle|some-toggle> in *development* environment in project *default*",
+}
+`;
+
+exports[`Should post to all channels in tags 1`] = `
+{
+  "attachments": [
+    {
+      "actions": [
+        {
+          "name": "featureToggle",
+          "style": "primary",
+          "text": "Open in Unleash",
+          "type": "button",
+          "url": "http://some-url.com/projects/default/features/some-toggle",
+          "value": "featureToggle",
+        },
+      ],
+    },
+  ],
+  "channel": 1,
+  "text": "some@user.com *enabled* <http://some-url.com/projects/default/features/some-toggle|some-toggle> in *development* environment in project *default*",
+}
+`;
+
+exports[`Should post to all channels in tags 2`] = `
+{
+  "attachments": [
+    {
+      "actions": [
+        {
+          "name": "featureToggle",
+          "style": "primary",
+          "text": "Open in Unleash",
+          "type": "button",
+          "url": "http://some-url.com/projects/default/features/some-toggle",
+          "value": "featureToggle",
+        },
+      ],
+    },
+  ],
+  "channel": 2,
+  "text": "some@user.com *enabled* <http://some-url.com/projects/default/features/some-toggle|some-toggle> in *development* environment in project *default*",
+}
+`;
diff --git a/src/lib/addons/slack-app.test.ts b/src/lib/addons/slack-app.test.ts
new file mode 100644
index 0000000000..73880612bd
--- /dev/null
+++ b/src/lib/addons/slack-app.test.ts
@@ -0,0 +1,123 @@
+import { IEvent, FEATURE_ENVIRONMENT_ENABLED } from '../types/events';
+
+import SlackAppAddon from './slack-app';
+
+import noLogger from '../../test/fixtures/no-logger';
+import { ChatPostMessageArguments } from '@slack/web-api';
+
+const accessToken = 'test-access-token';
+const slackApiCalls: ChatPostMessageArguments[] = [];
+jest.mock('@slack/web-api', () => ({
+    WebClient: jest.fn().mockImplementation(() => ({
+        conversations: {
+            list: () => ({
+                channels: [
+                    {
+                        id: 1,
+                        name: 'general',
+                    },
+                    {
+                        id: 2,
+                        name: 'another-channel-1',
+                    },
+                ],
+            }),
+        },
+        chat: {
+            postMessage: jest.fn().mockImplementation((options) => {
+                slackApiCalls.push(options);
+                return Promise.resolve();
+            }),
+        },
+    })),
+}));
+
+beforeEach(() => {
+    slackApiCalls.length = 0;
+});
+
+test('Should post message when feature is toggled', async () => {
+    const addon = new SlackAppAddon({
+        getLogger: noLogger,
+        unleashUrl: 'http://some-url.com',
+    });
+    const event: IEvent = {
+        id: 1,
+        createdAt: new Date(),
+        type: FEATURE_ENVIRONMENT_ENABLED,
+        createdBy: 'some@user.com',
+        project: 'default',
+        featureName: 'some-toggle',
+        environment: 'development',
+        data: {
+            name: 'some-toggle',
+            enabled: false,
+            type: 'release',
+            strategies: [{ name: 'default' }],
+        },
+        tags: [{ type: 'slack', value: 'general' }],
+    };
+
+    await addon.handleEvent(event, { accessToken });
+    expect(slackApiCalls.length).toBe(1);
+    expect(slackApiCalls[0].channel).toBe(1);
+    expect(slackApiCalls[0]).toMatchSnapshot();
+});
+
+test('Should post to all channels in tags', async () => {
+    const addon = new SlackAppAddon({
+        getLogger: noLogger,
+        unleashUrl: 'http://some-url.com',
+    });
+    const event: IEvent = {
+        id: 2,
+        createdAt: new Date(),
+        type: FEATURE_ENVIRONMENT_ENABLED,
+        createdBy: 'some@user.com',
+        project: 'default',
+        featureName: 'some-toggle',
+        environment: 'development',
+        data: {
+            name: 'some-toggle',
+        },
+        tags: [
+            { type: 'slack', value: 'general' },
+            { type: 'slack', value: 'another-channel-1' },
+        ],
+    };
+
+    await addon.handleEvent(event, { accessToken });
+    expect(slackApiCalls.length).toBe(2);
+    expect(slackApiCalls[0].channel).toBe(1);
+    expect(slackApiCalls[0]).toMatchSnapshot();
+    expect(slackApiCalls[1].channel).toBe(2);
+    expect(slackApiCalls[1]).toMatchSnapshot();
+});
+
+test('Should not post to unexisting tagged channels', async () => {
+    const addon = new SlackAppAddon({
+        getLogger: noLogger,
+        unleashUrl: 'http://some-url.com',
+    });
+    const event: IEvent = {
+        id: 3,
+        createdAt: new Date(),
+        type: FEATURE_ENVIRONMENT_ENABLED,
+        createdBy: 'some@user.com',
+        project: 'default',
+        featureName: 'some-toggle',
+        environment: 'development',
+        data: {
+            name: 'some-toggle',
+        },
+        tags: [
+            { type: 'slack', value: 'random' },
+            { type: 'slack', value: 'another-channel-1' },
+        ],
+    };
+
+    await addon.handleEvent(event, { accessToken });
+    expect(slackApiCalls.length).toBe(1);
+    expect(slackApiCalls[0].channel).toBe(2);
+    expect(slackApiCalls[0]).toMatchSnapshot();
+});