diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 282794af3..8fd67b8e5 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,6 +17,7 @@ jobs:
           node-version: '12.x'
       - uses: actions/checkout@v2
         with:
+          # needed for yarn version check, checks out entire repo
           fetch-depth: 0
       - name: Check yarn cache integrity
         run: yarn install --immutable --immutable-cache --check-cache
diff --git a/package.json b/package.json
index d09aab8b1..bd6bf936d 100644
--- a/package.json
+++ b/package.json
@@ -30,7 +30,8 @@
     "clean": "lerna run clean",
     "prepare": "lerna run prepare",
     "prettier": "prettier --config .prettierrc --write **/*.js",
-    "test": "lerna run test"
+    "test": "lerna run test",
+    "test:ci": "yarn install --immutable --immutable-cache --check-cache &&  yarn version check && yarn build && yarn test --ignore='@lowdefy/format'"
   },
   "devDependencies": {
     "@yarnpkg/pnpify": "2.3.3",
diff --git a/packages/cli/.babelrc b/packages/cli/.babelrc
index 41046be8a..16c7739be 100644
--- a/packages/cli/.babelrc
+++ b/packages/cli/.babelrc
@@ -7,6 +7,7 @@
           "node": "12"
         }
       }
-    ]
+    ],
+    "@babel/preset-react"
   ]
 }
diff --git a/packages/cli/src/commands/build/build.js b/packages/cli/src/commands/build/build.js
index 7c0024415..8690e435d 100644
--- a/packages/cli/src/commands/build/build.js
+++ b/packages/cli/src/commands/build/build.js
@@ -22,13 +22,15 @@ import { outputDirectoryPath } from '../../utils/directories';
 async function build(options) {
   const context = await createContext(options);
   await getBuildScript(context);
+  const outputDirectory = path.resolve(context.baseDirectory, outputDirectoryPath);
   context.print.info('Starting build.');
   await context.buildScript({
     logger: context.print,
     cacheDirectory: context.cacheDirectory,
     configDirectory: context.baseDirectory,
-    outputDirectory: path.resolve(context.baseDirectory, outputDirectoryPath),
+    outputDirectory,
   });
+  context.print.info(`Build artifacts saved at ${outputDirectory}.`);
 }
 
 export default build;
diff --git a/packages/cli/src/commands/cleanCache/cleanCache.test.js b/packages/cli/src/commands/cleanCache/cleanCache.test.js
new file mode 100644
index 000000000..69babb06c
--- /dev/null
+++ b/packages/cli/src/commands/cleanCache/cleanCache.test.js
@@ -0,0 +1,57 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+import path from 'path';
+import { cleanDirectory } from '@lowdefy/node-utils';
+import cleanCache from './cleanCache';
+import createPrint from '../../utils/print';
+
+jest.mock('@lowdefy/node-utils', () => {
+  const cleanDirectory = jest.fn();
+  return { cleanDirectory };
+});
+
+jest.mock('../../utils/print', () => {
+  const info = jest.fn();
+  return () => ({
+    info,
+  });
+});
+
+const print = createPrint();
+
+beforeEach(() => {
+  cleanDirectory.mockReset();
+});
+
+test('cleanCache', async () => {
+  await cleanCache({});
+  const cachePath = path.resolve(process.cwd(), './.lowdefy/.cache');
+  expect(cleanDirectory.mock.calls).toEqual([[cachePath]]);
+  expect(print.info.mock.calls).toEqual([
+    [`Cleaning cache at "${cachePath}".`],
+    ['Cache cleaned.'],
+  ]);
+});
+
+test('cleanCache baseDir', async () => {
+  await cleanCache({ baseDirectory: 'baseDir' });
+  const cachePath = path.resolve(process.cwd(), 'baseDir/.lowdefy/.cache');
+  expect(cleanDirectory.mock.calls).toEqual([[cachePath]]);
+  expect(print.info.mock.calls).toEqual([
+    [`Cleaning cache at "${cachePath}".`],
+    ['Cache cleaned.'],
+  ]);
+});
diff --git a/packages/cli/src/commands/dev/shell/index.html b/packages/cli/src/commands/dev/shell/index.html
index 08d78fc43..1252121c3 100644
--- a/packages/cli/src/commands/dev/shell/index.html
+++ b/packages/cli/src/commands/dev/shell/index.html
@@ -1,3 +1,18 @@
+<!--
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License. -->
+
 <!DOCTYPE html>
 <html lang="en">
   <head>
diff --git a/packages/cli/src/utils/BatchChanges.test.js b/packages/cli/src/utils/BatchChanges.test.js
new file mode 100644
index 000000000..88873aebc
--- /dev/null
+++ b/packages/cli/src/utils/BatchChanges.test.js
@@ -0,0 +1,188 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+import BatchChanges from './BatchChanges';
+
+async function wait(ms) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
+const context = {};
+
+test('BatchChanges calls the provided sync function', async () => {
+  const fn = jest.fn();
+  const batchChanges = new BatchChanges({ fn, context });
+  batchChanges.newChange();
+  await wait(600);
+  expect(fn).toHaveBeenCalledTimes(1);
+});
+
+test('BatchChanges calls the provided async function', async () => {
+  let done = false;
+  const fn = jest.fn(async () => {
+    await wait(100);
+    done = true;
+  });
+  const batchChanges = new BatchChanges({ fn, context });
+  batchChanges.newChange();
+  await wait(550);
+  expect(fn).toHaveBeenCalledTimes(1);
+  expect(done).toBe(false);
+  await wait(70);
+  expect(done).toBe(true);
+});
+
+test('BatchChanges calls the provided sync function only once if newChange is called multiple times', async () => {
+  const fn = jest.fn();
+  const batchChanges = new BatchChanges({ fn, context });
+  batchChanges.newChange();
+  batchChanges.newChange();
+  batchChanges.newChange();
+  await wait(600);
+  expect(fn).toHaveBeenCalledTimes(1);
+});
+
+test('BatchChanges has a default minDelay', async () => {
+  const fn = jest.fn();
+  const batchChanges = new BatchChanges({ fn, context });
+  expect(batchChanges.minDelay).toBe(500);
+  expect(batchChanges.delay).toBe(500);
+});
+
+test('BatchChanges set minDelay', async () => {
+  const fn = jest.fn();
+  const batchChanges = new BatchChanges({ fn, context, minDelay: 42 });
+  expect(batchChanges.minDelay).toBe(42);
+  expect(batchChanges.delay).toBe(42);
+});
+
+test('BatchChanges resets timer if newChange is called multiple times in delay window', async () => {
+  const fn = jest.fn();
+  const batchChanges = new BatchChanges({ fn, context });
+  batchChanges.newChange();
+  await wait(400);
+  batchChanges.newChange();
+  await wait(400);
+  batchChanges.newChange();
+  await wait(600);
+  expect(fn).toHaveBeenCalledTimes(1);
+});
+
+test('BatchChanges retries on errors, with back-off', async () => {
+  let count = 0;
+  let success = false;
+  const context = {
+    print: {
+      error: jest.fn(),
+      warn: jest.fn(),
+    },
+  };
+  const fn = jest.fn(() => {
+    if (count > 1) {
+      success = true;
+      return;
+    }
+    count += 1;
+    throw new Error(`Error: ${count}`);
+  });
+  const batchChanges = new BatchChanges({ fn, context, minDelay: 100 });
+  batchChanges.newChange();
+  await wait(120);
+  expect(fn).toHaveBeenCalledTimes(1);
+  expect(context.print.error.mock.calls).toEqual([
+    [
+      'Error: 1',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(context.print.warn.mock.calls).toEqual([
+    [
+      'Retrying in 0.2s.',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(batchChanges.delay).toBe(200);
+  expect(count).toBe(1);
+  await wait(200);
+  expect(fn).toHaveBeenCalledTimes(2);
+  expect(context.print.error.mock.calls).toEqual([
+    [
+      'Error: 1',
+      {
+        timestamp: true,
+      },
+    ],
+    [
+      'Error: 2',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(context.print.warn.mock.calls).toEqual([
+    [
+      'Retrying in 0.2s.',
+      {
+        timestamp: true,
+      },
+    ],
+    [
+      'Retrying in 0.4s.',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(batchChanges.delay).toBe(400);
+  expect(count).toBe(2);
+  await wait(400);
+  expect(fn).toHaveBeenCalledTimes(3);
+  expect(context.print.error.mock.calls).toEqual([
+    [
+      'Error: 1',
+      {
+        timestamp: true,
+      },
+    ],
+    [
+      'Error: 2',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(context.print.warn.mock.calls).toEqual([
+    [
+      'Retrying in 0.2s.',
+      {
+        timestamp: true,
+      },
+    ],
+    [
+      'Retrying in 0.4s.',
+      {
+        timestamp: true,
+      },
+    ],
+  ]);
+  expect(success).toBe(true);
+});
diff --git a/packages/cli/src/utils/context.js b/packages/cli/src/utils/context.js
index f2cd10d8b..b7185c343 100644
--- a/packages/cli/src/utils/context.js
+++ b/packages/cli/src/utils/context.js
@@ -19,7 +19,7 @@ import getLowdefyVersion from './getLowdefyVersion';
 import createPrint from './print';
 import { cacheDirectoryPath } from './directories';
 
-async function createContext(options) {
+async function createContext(options = {}) {
   const context = {
     baseDirectory: path.resolve(options.baseDirectory || process.cwd()),
     print: createPrint({ timestamp: true }),
diff --git a/packages/cli/src/utils/context.test.js b/packages/cli/src/utils/context.test.js
new file mode 100644
index 000000000..020ccf35d
--- /dev/null
+++ b/packages/cli/src/utils/context.test.js
@@ -0,0 +1,55 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+import path from 'path';
+import createContext from './context';
+// eslint-disable-next-line no-unused-vars
+import getLowdefyVersion from './getLowdefyVersion';
+// eslint-disable-next-line no-unused-vars
+import createPrint from './print';
+
+jest.mock('./getLowdefyVersion', () => async () => Promise.resolve('lowdefy-version'));
+jest.mock('./print', () => () => 'print');
+
+test('createContext, options undefined', async () => {
+  const context = await createContext();
+  expect(context).toEqual({
+    baseDirectory: path.resolve(process.cwd()),
+    cacheDirectory: path.resolve(process.cwd(), './.lowdefy/.cache'),
+    version: 'lowdefy-version',
+    print: 'print',
+  });
+});
+
+test('createContext, options empty', async () => {
+  const context = await createContext({});
+  expect(context).toEqual({
+    baseDirectory: path.resolve(process.cwd()),
+    cacheDirectory: path.resolve(process.cwd(), './.lowdefy/.cache'),
+    version: 'lowdefy-version',
+    print: 'print',
+  });
+});
+
+test('createContext, options baseDir', async () => {
+  const context = await createContext({ baseDirectory: 'baseDir' });
+  expect(context).toEqual({
+    baseDirectory: path.resolve(process.cwd(), 'baseDir'),
+    cacheDirectory: path.resolve(process.cwd(), 'baseDir/.lowdefy/.cache'),
+    version: 'lowdefy-version',
+    print: 'print',
+  });
+});
diff --git a/packages/cli/src/utils/directories.js b/packages/cli/src/utils/directories.js
index ad6820e35..76c127959 100644
--- a/packages/cli/src/utils/directories.js
+++ b/packages/cli/src/utils/directories.js
@@ -1,3 +1,19 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
 const cacheDirectoryPath = './.lowdefy/.cache';
 const outputDirectoryPath = './.lowdefy/build';
 
diff --git a/packages/cli/src/utils/directories.test.js b/packages/cli/src/utils/directories.test.js
new file mode 100644
index 000000000..772204cd5
--- /dev/null
+++ b/packages/cli/src/utils/directories.test.js
@@ -0,0 +1,24 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+import * as directories from './directories';
+
+test('directories', () => {
+  expect(directories).toEqual({
+    cacheDirectoryPath: './.lowdefy/.cache',
+    outputDirectoryPath: './.lowdefy/build',
+  });
+});
diff --git a/packages/cli/src/utils/errorHandler.js b/packages/cli/src/utils/errorHandler.js
index c604ef3f3..88a686934 100644
--- a/packages/cli/src/utils/errorHandler.js
+++ b/packages/cli/src/utils/errorHandler.js
@@ -24,6 +24,7 @@ function errorHandler(fn, options = {}) {
     } catch (error) {
       const print = createPrint();
       print.error(error.message);
+      // TODO: Stay alive feature
     }
   }
   return run;
diff --git a/packages/cli/src/utils/errorHandler.test.js b/packages/cli/src/utils/errorHandler.test.js
index 2b7736ba3..77396a20d 100644
--- a/packages/cli/src/utils/errorHandler.test.js
+++ b/packages/cli/src/utils/errorHandler.test.js
@@ -62,33 +62,7 @@ test('Pass args to synchronous function', async () => {
   expect(res).toEqual({ arg1: '1', arg2: '2' });
 });
 
-test('Catch error synchronous function, stay alive', async () => {
-  const fn = jest.fn(() => {
-    throw new Error('Error');
-  });
-  const wrapped = errorHandler(fn, { stayAlive: true });
-  const res = await wrapped();
-  expect(res).toBe(undefined);
-  expect(fn).toHaveBeenCalled();
-  expect(print.error.mock.calls).toEqual([['Error']]);
-});
-
-test('Catch error asynchronous function, stay alive', async () => {
-  const fn = jest.fn(async () => {
-    await wait(3);
-    throw new Error('Async Error');
-  });
-  const wrapped = errorHandler(fn, { stayAlive: true });
-  const res = await wrapped();
-  expect(res).toBe(undefined);
-  expect(fn).toHaveBeenCalled();
-  expect(print.error.mock.calls).toEqual([['Async Error']]);
-});
-
-test('Catch error synchronous function, exit process', async () => {
-  const realExit = process.exit;
-  const mockExit = jest.fn();
-  process.exit = mockExit;
+test('Catch error synchronous function', async () => {
   const fn = jest.fn(() => {
     throw new Error('Error');
   });
@@ -96,14 +70,9 @@ test('Catch error synchronous function, exit process', async () => {
   await wrapped();
   expect(fn).toHaveBeenCalled();
   expect(print.error.mock.calls).toEqual([['Error']]);
-  expect(mockExit).toHaveBeenCalled();
-  process.exit = realExit;
 });
 
-test('Catch error asynchronous function, exit process', async () => {
-  const realExit = process.exit;
-  const mockExit = jest.fn();
-  process.exit = mockExit;
+test('Catch error asynchronous function', async () => {
   const fn = jest.fn(async () => {
     await wait(3);
     throw new Error('Async Error');
@@ -112,6 +81,27 @@ test('Catch error asynchronous function, exit process', async () => {
   await wrapped();
   expect(fn).toHaveBeenCalled();
   expect(print.error.mock.calls).toEqual([['Async Error']]);
-  expect(mockExit).toHaveBeenCalled();
-  process.exit = realExit;
 });
+
+// test('Catch error synchronous function, stay alive', async () => {
+//   const fn = jest.fn(() => {
+//     throw new Error('Error');
+//   });
+//   const wrapped = errorHandler(fn, { stayAlive: true });
+//   const res = await wrapped();
+//   expect(res).toBe(undefined);
+//   expect(fn).toHaveBeenCalled();
+//   expect(print.error.mock.calls).toEqual([['Error']]);
+// });
+
+// test('Catch error asynchronous function, stay alive', async () => {
+//   const fn = jest.fn(async () => {
+//     await wait(3);
+//     throw new Error('Async Error');
+//   });
+//   const wrapped = errorHandler(fn, { stayAlive: true });
+//   const res = await wrapped();
+//   expect(res).toBe(undefined);
+//   expect(fn).toHaveBeenCalled();
+//   expect(print.error.mock.calls).toEqual([['Async Error']]);
+// });
diff --git a/packages/cli/src/utils/getLowdefyVersion.js b/packages/cli/src/utils/getLowdefyVersion.js
index 555b47d89..5233c3e28 100644
--- a/packages/cli/src/utils/getLowdefyVersion.js
+++ b/packages/cli/src/utils/getLowdefyVersion.js
@@ -19,7 +19,7 @@ import { type } from '@lowdefy/helpers';
 import { readFile } from '@lowdefy/node-utils';
 import YAML from 'js-yaml';
 
-async function getLowdefyVersion(context) {
+async function getLowdefyVersion(context = {}) {
   const lowdefyYaml = await readFile(
     path.resolve(context.baseDirectory || process.cwd(), 'lowdefy.yaml')
   );
diff --git a/packages/cli/src/utils/getLowdefyVersion.test.js b/packages/cli/src/utils/getLowdefyVersion.test.js
index 637524144..ca75f73a3 100644
--- a/packages/cli/src/utils/getLowdefyVersion.test.js
+++ b/packages/cli/src/utils/getLowdefyVersion.test.js
@@ -30,6 +30,19 @@ beforeEach(() => {
 });
 
 test('get version from yaml file', async () => {
+  readFile.mockImplementation((filePath) => {
+    if (filePath === path.resolve(process.cwd(), 'lowdefy.yaml')) {
+      return `
+      version: 1.0.0
+      `;
+    }
+    return null;
+  });
+  const version = await getLowdefyVersion({});
+  expect(version).toEqual('1.0.0');
+});
+
+test('get version from yaml file, context default value', async () => {
   readFile.mockImplementation((filePath) => {
     if (filePath === path.resolve(process.cwd(), 'lowdefy.yaml')) {
       return `
@@ -51,7 +64,7 @@ test('get version from yaml file, base dir specified', async () => {
     }
     return null;
   });
-  const version = await getLowdefyVersion('./baseDir');
+  const version = await getLowdefyVersion({ baseDirectory: './baseDir' });
   expect(version).toEqual('1.0.0');
 });
 
@@ -64,7 +77,7 @@ test('could not find lowdefy.yaml in cwd', async () => {
     version: 1.0.0
     `;
   });
-  await expect(getLowdefyVersion()).rejects.toThrow(
+  await expect(getLowdefyVersion({})).rejects.toThrow(
     'Could not find "lowdefy.yaml" file in current working directory. Change directory to a Lowdefy project, or specify a base directory.'
   );
 });
@@ -78,7 +91,7 @@ test('could not find lowdefy.yaml in base dir', async () => {
     version: 1.0.0
     `;
   });
-  await expect(getLowdefyVersion('./baseDir')).rejects.toThrow(
+  await expect(getLowdefyVersion({ baseDirectory: './baseDir' })).rejects.toThrow(
     'Could not find "lowdefy.yaml" file in specified base directory'
   );
 });
@@ -94,7 +107,7 @@ test('lowdefy.yaml is invalid yaml', async () => {
     }
     return null;
   });
-  await expect(getLowdefyVersion()).rejects.toThrow(
+  await expect(getLowdefyVersion({})).rejects.toThrow(
     'Could not parse "lowdefy.yaml" file. Received error '
   );
 });
@@ -110,7 +123,7 @@ test('No version specified', async () => {
     }
     return null;
   });
-  await expect(getLowdefyVersion()).rejects.toThrow(
+  await expect(getLowdefyVersion({})).rejects.toThrow(
     'No version specified in "lowdefy.yaml" file. Specify a version in the "version field".'
   );
 });
@@ -124,7 +137,7 @@ test('Version is not a string', async () => {
     }
     return null;
   });
-  await expect(getLowdefyVersion()).rejects.toThrow(
+  await expect(getLowdefyVersion({})).rejects.toThrow(
     'Version number specified in "lowdefy.yaml" file is not valid. Received 1.'
   );
 });
@@ -138,7 +151,7 @@ test('Version is not a valid version number', async () => {
     }
     return null;
   });
-  await expect(getLowdefyVersion()).rejects.toThrow(
+  await expect(getLowdefyVersion({})).rejects.toThrow(
     'Version number specified in "lowdefy.yaml" file is not valid. Received "v1-0-3".'
   );
 });
diff --git a/packages/cli/src/utils/print.js b/packages/cli/src/utils/print.js
index 8f248d674..1441f409c 100644
--- a/packages/cli/src/utils/print.js
+++ b/packages/cli/src/utils/print.js
@@ -19,7 +19,7 @@ import chalk from 'chalk';
 const printToTerminal = (color, options = {}) => (text) => {
   let message;
   if (options.timestamp) {
-    const time = options.timestamp === true ? new Date(Date.now()) : new Date(options.timestamp);
+    const time = new Date(Date.now());
     const h = time.getHours();
     const m = time.getMinutes();
     const s = time.getSeconds();
diff --git a/packages/cli/src/utils/print.test.js b/packages/cli/src/utils/print.test.js
new file mode 100644
index 000000000..79db09e89
--- /dev/null
+++ b/packages/cli/src/utils/print.test.js
@@ -0,0 +1,153 @@
+/*
+  Copyright 2020 Lowdefy, Inc
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+import createPrint from './print';
+
+const mockConsoleLog = jest.fn();
+const mockGetHours = jest.fn();
+const mockGetMinutes = jest.fn();
+const mockGetSeconds = jest.fn();
+// const realLog = console.log;
+// const realNow = Date.now;
+console.log = mockConsoleLog;
+// eslint-disable-next-line no-global-assign
+Date = jest.fn(() => ({
+  getHours: mockGetHours,
+  getMinutes: mockGetMinutes,
+  getSeconds: mockGetSeconds,
+}));
+
+Date.now = () => {};
+
+beforeEach(() => {
+  mockConsoleLog.mockReset();
+  mockGetHours.mockReset();
+  mockGetMinutes.mockReset();
+  mockGetSeconds.mockReset();
+});
+
+// afterAll(() => {
+//   console.log = realLog;
+//   Date.now = realNow;
+// });
+
+test('create print', () => {
+  const print = createPrint();
+  expect(print).toMatchInlineSnapshot(`
+    Object {
+      "error": [Function],
+      "info": [Function],
+      "log": [Function],
+      "warn": [Function],
+    }
+  `);
+});
+
+test('print info', () => {
+  const print = createPrint();
+  print.info('Test info');
+  expect(mockConsoleLog.mock.calls).toEqual([['Test info']]);
+});
+
+test('print log', () => {
+  const print = createPrint();
+  print.log('Test log');
+  expect(mockConsoleLog.mock.calls).toEqual([['Test log']]);
+});
+
+test('print warn', () => {
+  const print = createPrint();
+  print.warn('Test warn');
+  expect(mockConsoleLog.mock.calls).toEqual([['Test warn']]);
+});
+
+test('print error', () => {
+  const print = createPrint();
+  print.error('Test error');
+  expect(mockConsoleLog.mock.calls).toEqual([['Test error']]);
+});
+
+test('print info with timestamp, less than 10', () => {
+  mockGetHours.mockImplementation(() => 1);
+  mockGetMinutes.mockImplementation(() => 2);
+  mockGetSeconds.mockImplementation(() => 3);
+  const print = createPrint({ timestamp: true });
+  print.info('Test info');
+  expect(mockConsoleLog.mock.calls).toEqual([['01:02:03 - Test info']]);
+});
+
+test('print log with timestamp, less than 10', () => {
+  mockGetHours.mockImplementation(() => 1);
+  mockGetMinutes.mockImplementation(() => 2);
+  mockGetSeconds.mockImplementation(() => 3);
+  const print = createPrint({ timestamp: true });
+  print.log('Test log');
+  expect(mockConsoleLog.mock.calls).toEqual([['01:02:03 - Test log']]);
+});
+
+test('print warn with timestamp, less than 10', () => {
+  mockGetHours.mockImplementation(() => 1);
+  mockGetMinutes.mockImplementation(() => 2);
+  mockGetSeconds.mockImplementation(() => 3);
+  const print = createPrint({ timestamp: true });
+  print.warn('Test warn');
+  expect(mockConsoleLog.mock.calls).toEqual([['01:02:03 - Test warn']]);
+});
+
+test('print error with timestamp, less than 10', () => {
+  mockGetHours.mockImplementation(() => 1);
+  mockGetMinutes.mockImplementation(() => 2);
+  mockGetSeconds.mockImplementation(() => 3);
+  const print = createPrint({ timestamp: true });
+  print.error('Test error');
+  expect(mockConsoleLog.mock.calls).toEqual([['01:02:03 - Test error']]);
+});
+
+test('print info with timestamp, two digits', () => {
+  mockGetHours.mockImplementation(() => 11);
+  mockGetMinutes.mockImplementation(() => 22);
+  mockGetSeconds.mockImplementation(() => 33);
+  const print = createPrint({ timestamp: true });
+  print.info('Test info');
+  expect(mockConsoleLog.mock.calls).toEqual([['11:22:33 - Test info']]);
+});
+
+test('print log with timestamp, two digits', () => {
+  mockGetHours.mockImplementation(() => 11);
+  mockGetMinutes.mockImplementation(() => 22);
+  mockGetSeconds.mockImplementation(() => 33);
+  const print = createPrint({ timestamp: true });
+  print.log('Test log');
+  expect(mockConsoleLog.mock.calls).toEqual([['11:22:33 - Test log']]);
+});
+
+test('print warn with timestamp, two digits', () => {
+  mockGetHours.mockImplementation(() => 11);
+  mockGetMinutes.mockImplementation(() => 22);
+  mockGetSeconds.mockImplementation(() => 33);
+  const print = createPrint({ timestamp: true });
+  print.warn('Test warn');
+  expect(mockConsoleLog.mock.calls).toEqual([['11:22:33 - Test warn']]);
+});
+
+test('print error with timestamp, two digits', () => {
+  mockGetHours.mockImplementation(() => 11);
+  mockGetMinutes.mockImplementation(() => 22);
+  mockGetSeconds.mockImplementation(() => 33);
+  const print = createPrint({ timestamp: true });
+  print.error('Test error');
+  expect(mockConsoleLog.mock.calls).toEqual([['11:22:33 - Test error']]);
+});