diff --git a/package.json b/package.json
index 471e3eb4..ed599639 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
   "license": "MIT",
   "devDependencies": {
     "chai": "^4.2.0",
+    "chai-as-promised": "^7.1.1",
     "eslint": "^6.0.1",
     "eslint-config-hexo": "^3.0.0",
     "html-tag-validator": "^1.5.0",
diff --git a/test/scripts/cache_stream.js b/test/scripts/cache_stream.js
index 6fab3f1b..3e80262e 100644
--- a/test/scripts/cache_stream.js
+++ b/test/scripts/cache_stream.js
@@ -1,5 +1,7 @@
 'use strict';
 
+require('chai').should();
+
 const { Readable } = require('stream');
 
 describe('CacheStream', () => {
diff --git a/test/scripts/camel_case_keys.js b/test/scripts/camel_case_keys.js
index e8b0ba6a..d936e525 100644
--- a/test/scripts/camel_case_keys.js
+++ b/test/scripts/camel_case_keys.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('camelCaseKeys', () => {
   const camelCaseKeys = require('../../lib/camel_case_keys');
@@ -17,11 +17,7 @@ describe('camelCaseKeys', () => {
   });
 
   it('obj must be an object', () => {
-    try {
-      camelCaseKeys();
-    } catch (err) {
-      err.should.have.property('message', 'obj must be an object!');
-    }
+    camelCaseKeys.should.throw('obj must be an object!');
   });
 
   it('setter', () => {
@@ -48,12 +44,7 @@ describe('camelCaseKeys', () => {
   });
 
   it('do nothing if the key is camelCase', () => {
-    const result = camelCaseKeys({
-      fooBar: 'test'
-    });
-
-    result.should.eql({
-      fooBar: 'test'
-    });
+    const result = camelCaseKeys({ fooBar: 'test' });
+    result.should.eql({ fooBar: 'test' });
   });
 });
diff --git a/test/scripts/color.js b/test/scripts/color.js
index 898777f7..3f943fb3 100644
--- a/test/scripts/color.js
+++ b/test/scripts/color.js
@@ -1,5 +1,7 @@
 'use strict';
 
+require('chai').should();
+
 describe('color', () => {
   const Color = require('../../lib/color');
 
diff --git a/test/scripts/escape_diacritic.js b/test/scripts/escape_diacritic.js
index 60751910..d8579254 100644
--- a/test/scripts/escape_diacritic.js
+++ b/test/scripts/escape_diacritic.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('escapeDiacritic', () => {
   const escapeDiacritic = require('../../lib/escape_diacritic');
@@ -10,10 +10,6 @@ describe('escapeDiacritic', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      escapeDiacritic();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    escapeDiacritic.should.throw('str must be a string!');
   });
 });
diff --git a/test/scripts/escape_html.js b/test/scripts/escape_html.js
index 0207fc6f..25d64841 100644
--- a/test/scripts/escape_html.js
+++ b/test/scripts/escape_html.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('escapeHTML', () => {
   const escapeHTML = require('../../lib/escape_html');
@@ -10,10 +10,6 @@ describe('escapeHTML', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      escapeHTML();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    escapeHTML.should.throw('str must be a string!');
   });
 });
diff --git a/test/scripts/escape_regexp.js b/test/scripts/escape_regexp.js
index 7c3c5116..d9ad11b7 100644
--- a/test/scripts/escape_regexp.js
+++ b/test/scripts/escape_regexp.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('escapeRegExp', () => {
   const escapeRegExp = require('../../lib/escape_regexp');
@@ -10,10 +10,6 @@ describe('escapeRegExp', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      escapeRegExp();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    escapeRegExp.should.throw('str must be a string!');
   });
 });
diff --git a/test/scripts/hash.js b/test/scripts/hash.js
index 820eb254..eac02297 100644
--- a/test/scripts/hash.js
+++ b/test/scripts/hash.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 const crypto = require('crypto');
 
 function sha1(content) {
@@ -28,17 +28,17 @@ describe('hash', () => {
     stream.read().should.eql(sha1(content));
   });
 
-  it('createSha1Hash', function() {
-    var _sha1 = hash.createSha1Hash();
-    var content = '123456';
+  it('createSha1Hash', () => {
+    const _sha1 = hash.createSha1Hash();
+    const content = '123456';
     _sha1.update(content);
     _sha1.digest().should.eql(sha1(content));
   });
 
-  it('createSha1Hash - streamMode', function() {
-    var content1 = '123456';
-    var content2 = '654321';
-    var stream = hash.createSha1Hash();
+  it('createSha1Hash - streamMode', () => {
+    const content1 = '123456';
+    const content2 = '654321';
+    const stream = hash.createSha1Hash();
     // explicit convert
     stream.write(Buffer.from(content1));
     // implicit convert
diff --git a/test/scripts/highlight.js b/test/scripts/highlight.js
index 3fb23900..3e01edde 100644
--- a/test/scripts/highlight.js
+++ b/test/scripts/highlight.js
@@ -46,27 +46,14 @@ function code(str, lang) {
   }
 
   const lines = data.value.split('\n');
-  let result = codeStart;
 
-  for (let i = 0, len = lines.length; i < len; i++) {
-    result += `<span class="line">${lines[i]}</span><br>`;
-  }
-
-  result += codeEnd;
-
-  return result;
+  return lines.reduce((prev, current) => {
+    return `${prev}<span class="line">${current}</span><br>`;
+  }, codeStart) + codeEnd;
 }
 
-function assertResult(result) {
-  let expected = start;
-
-  for (let i = 1, len = arguments.length; i < len; i++) {
-    expected += arguments[i];
-  }
-
-  expected += end;
-
-  result.should.eql(expected);
+function assertResult(result, ...args) {
+  result.should.eql(start + args.join('') + end);
 }
 
 function validateHtmlAsync(str, done) {
@@ -89,11 +76,7 @@ describe('highlight', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      highlight();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    highlight.should.throw('str must be a string!');
   });
 
   it('gutter: false', done => {
diff --git a/test/scripts/html_tag.js b/test/scripts/html_tag.js
index 67b2470b..b719d33b 100644
--- a/test/scripts/html_tag.js
+++ b/test/scripts/html_tag.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('htmlTag', () => {
   const htmlTag = require('../../lib/html_tag');
diff --git a/test/scripts/pattern.js b/test/scripts/pattern.js
index a21010d9..d2e99635 100644
--- a/test/scripts/pattern.js
+++ b/test/scripts/pattern.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('Pattern', () => {
   const Pattern = require('../../lib/pattern');
@@ -60,11 +60,9 @@ describe('Pattern', () => {
   });
 
   it('rule is required', () => {
-    try {
+    (() => {
       // eslint-disable-next-line no-new
       new Pattern();
-    } catch (err) {
-      err.should.have.property('message', 'rule must be a function, a string or a regular expression.');
-    }
+    }).should.throw('rule must be a function, a string or a regular expression.');
   });
 });
diff --git a/test/scripts/permalink.js b/test/scripts/permalink.js
index dbad6837..4ce6a6e2 100644
--- a/test/scripts/permalink.js
+++ b/test/scripts/permalink.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('Permalink', () => {
   const Permalink = require('../../lib/permalink');
diff --git a/test/scripts/slugize.js b/test/scripts/slugize.js
index e4ddde89..d1db5442 100644
--- a/test/scripts/slugize.js
+++ b/test/scripts/slugize.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('slugize', () => {
   const slugize = require('../../lib/slugize');
@@ -42,10 +42,6 @@ describe('slugize', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      slugize();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    slugize.should.throw('str must be a string!');
   });
 });
diff --git a/test/scripts/spawn.js b/test/scripts/spawn.js
index 947c3d9b..7d21e909 100644
--- a/test/scripts/spawn.js
+++ b/test/scripts/spawn.js
@@ -1,8 +1,8 @@
 'use strict';
 
-const should = require('chai').should();
-const pathFn = require('path');
-const fs = require('fs');
+require('chai').use(require('chai-as-promised')).should();
+const { join } = require('path');
+const { writeFile, unlink } = require('fs');
 const rewire = require('rewire');
 
 const isWindows = process.platform === 'win32';
@@ -11,34 +11,30 @@ const catCommand = isWindows ? 'type' : 'cat';
 describe('spawn', () => {
   const spawn = require('../../lib/spawn');
   const CacheStream = require('../../lib/cache_stream');
-  const fixturePath = pathFn.join(__dirname, 'spawn_test.txt');
+  const fixturePath = join(__dirname, 'spawn_test.txt');
   const fixture = 'test content';
 
   before(done => {
-    fs.writeFile(fixturePath, fixture, done);
+    writeFile(fixturePath, fixture, done);
   });
 
   after(done => {
-    fs.unlink(fixturePath, done);
+    unlink(fixturePath, done);
   });
 
-  it('default', () => spawn(catCommand, [fixturePath]).then(content => {
-    content.should.eql(fixture);
-  }));
+  it('default', () => spawn(catCommand, [fixturePath]).should.become(fixture));
 
   it('command is required', () => {
     spawn.should.throw('command is required!');
   });
 
-  it('error', () => spawn(catCommand, ['nothing']).then(() => should.fail(`expected spawn(${catCommand}, ['nothing']) to throw an error`), err => {
+  it('error', () => {
+    const promise = spawn(catCommand, ['nothing']);
     if (isWindows) {
-      err.message.trim().should.eql('spawn type ENOENT');
-      err.code.should.eql('ENOENT');
-    } else {
-      err.message.trim().should.eql('cat: nothing: No such file or directory');
-      err.code.should.eql(1);
+      return promise.should.rejectedWith('spawn type ENOENT').and.eventually.have.property('code', 'ENOENT');
     }
-  }));
+    return promise.should.rejectedWith('cat: nothing: No such file or directory').and.eventually.have.property('code', 1);
+  });
 
   it('verbose - stdout', () => {
     const spawn = rewire('../../lib/spawn');
@@ -48,10 +44,7 @@ describe('spawn', () => {
 
     spawn.__set__('process', Object.assign({}, process, {
       stdout: stdoutCache,
-      stderr: stderrCache,
-      removeListener: () => {},
-      on: () => {},
-      exit: () => {}
+      stderr: stderrCache
     }));
 
     return spawn('echo', [content], {
@@ -75,32 +68,29 @@ describe('spawn', () => {
       stdout: stdoutCache,
       stderr: stderrCache,
       removeListener: () => {},
-      on: () => {},
-      exit: () => {}
+      on: () => {}
     }));
 
     return spawn(catCommand, ['nothing'], {
       verbose: true
-    }).then(() => should.fail(`expected spawn(${catCommand}, ['nothing'], {verbose: true}) to throw an error`), () => {
+    }).should.rejected.then(() => {
       const stderrResult = stderrCache.getCache();
       if (isWindows) {
         // utf8 support in windows shell (cmd.exe) is difficult.
         Buffer.byteLength(stderrResult, 'hex').should.least(1);
       } else {
-        stderrResult.toString('utf8').trim().should.eql('cat: nothing: No such file or directory');
+        stderrResult.toString('utf8').should.with.match(/^cat: nothing: No such file or directory\n?$/);
       }
     });
   });
 
-  it('custom encoding', () => spawn(catCommand, [fixturePath], {encoding: 'hex'}).then(content => {
-    content.should.eql(Buffer.from(fixture).toString('hex'));
-  }));
+  it('custom encoding', () => {
+    return spawn(catCommand, [fixturePath], {encoding: 'hex'}).should.become(Buffer.from(fixture).toString('hex'));
+  });
 
-  it('encoding = null', () => spawn(catCommand, [fixturePath], {encoding: null}).then(content => {
-    content.should.eql(Buffer.from(fixture));
-  }));
+  it('encoding = null', () => {
+    return spawn(catCommand, [fixturePath], {encoding: null}).should.become(Buffer.from(fixture));
+  });
 
-  it('stdio = inherit', () => spawn('echo', ['something'], {
-    stdio: 'inherit'
-  }));
+  it('stdio = inherit', () => spawn('echo', ['something'], { stdio: 'inherit' }));
 });
diff --git a/test/scripts/truncate.js b/test/scripts/truncate.js
index a5f633fe..67a1cb2d 100644
--- a/test/scripts/truncate.js
+++ b/test/scripts/truncate.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('truncate', () => {
   const truncate = require('../../lib/truncate');
@@ -31,10 +31,6 @@ describe('truncate', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      truncate();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    truncate.should.throw('str must be a string!');
   });
 });
diff --git a/test/scripts/word_wrap.js b/test/scripts/word_wrap.js
index 96a52d89..0da8242f 100644
--- a/test/scripts/word_wrap.js
+++ b/test/scripts/word_wrap.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const should = require('chai').should(); // eslint-disable-line
+require('chai').should();
 
 describe('wordWrap', () => {
   const wordWrap = require('../../lib/word_wrap');
@@ -23,10 +23,6 @@ describe('wordWrap', () => {
   });
 
   it('str must be a string', () => {
-    try {
-      wordWrap();
-    } catch (err) {
-      err.should.have.property('message', 'str must be a string!');
-    }
+    wordWrap.should.throw('str must be a string!');
   });
 });