diff --git a/test/color.spec.js b/test/color.spec.js
index be5ae0e7..093c385c 100644
--- a/test/color.spec.js
+++ b/test/color.spec.js
@@ -51,5 +51,53 @@ describe('color', () => {
     `${steelblue}`.should.eql('#4682b4');
     `${mid1}`.should.eql('rgba(70, 130, 180, 0.53)');
     `${mid2}`.should.eql('rgba(70, 130, 180, 0.77)');
+
+    // s=0
+    const grey = new Color('hsl(207, 0%, 49%)');
+    // h=0
+    const red1 = new Color('hsl(0, 100%, 50%)');
+    // h=360
+    const red2 = new Color('hsl(360, 100%, 50%)');
+
+    `${grey}`.should.eql('#7d7d7d');
+    `${red1}`.should.eql('#f00');
+    `${red2}`.should.eql('#f00');
+  });
+
+  it('invalid color', () => {
+    let color;
+    try {
+      color = new Color(200);
+    } catch (e) {
+      e.message.should.eql('color is required!');
+    }
+    try {
+      color = new Color('rgb(300, 130, 180)');
+    } catch (e) {
+      e.message.should.eql('{r: 300, g: 130, b: 180, a: 1} is invalid.');
+    }
+    try {
+      color = new Color('cmyk(0%,0%,0%,0%)');
+    } catch (e) {
+      e.message.should.eql('cmyk(0%,0%,0%,0%) is not a supported color format.');
+    }
+    (typeof color).should.eql('undefined');
   });
+
+  it('mix()', () => {
+    const red = new Color('red');
+    const pink = new Color('pink');
+    const mid1 = red.mix(pink, 0);
+    const mid2 = red.mix(pink, 1);
+
+    `${mid1}`.should.eql('#f00');
+    `${mid2}`.should.eql('#ffc0cb');
+
+    try {
+      red.mix(pink, 2);
+    } catch (e) {
+      e.message.should.eql('Valid numbers is only between 0 and 1.');
+    }
+  });
+
 });
diff --git a/test/decode_url.spec.js b/test/decode_url.spec.js
index f3fa942f..d6bc3c3e 100644
--- a/test/decode_url.spec.js
+++ b/test/decode_url.spec.js
@@ -84,4 +84,9 @@ describe('decodeURL', () => {
     const content = '#f%C3%B3o-b%C3%A1r';
     decodeURL(content).should.eql('#fóo-bár');
   });
+
+  it('data url', () => {
+    const content = 'data:image/png;base64';
+    decodeURL(content).should.eql('data:image/png;base64');
+  });
 });
diff --git a/test/is_external_link.spec.js b/test/is_external_link.spec.js
index d72e0a0e..2b06821a 100644
--- a/test/is_external_link.spec.js
+++ b/test/is_external_link.spec.js
@@ -56,4 +56,11 @@ describe('isExternalLink', () => {
     isExternalLink('https://bar.com/', ctx.config.url, ctx.config.external_link.exclude).should.eql(false);
     isExternalLink('https://baz.com/', ctx.config.url, ctx.config.external_link.exclude).should.eql(true);
   });
+
+  it('invalid sitehost', () => {
+    ctx.config.url = '';
+    isExternalLink('https://localhost:4000', ctx.config.url).should.eql(false);
+    ctx.config.url = 'https://example.com';
+  });
+
 });
diff --git a/test/pattern.spec.js b/test/pattern.spec.js
index f3c8476b..75fa3d5a 100644
--- a/test/pattern.spec.js
+++ b/test/pattern.spec.js
@@ -59,10 +59,23 @@ describe('Pattern', () => {
     pattern.match('foo').should.eql({});
   });
 
+  it('Pattern', () => {
+    const pattern = new Pattern('posts/:id');
+    new Pattern(pattern).should.eql(pattern);
+  });
+
   it('rule is required', () => {
     (() => {
       // eslint-disable-next-line no-new
       new Pattern();
     }).should.throw('rule must be a function, a string or a regular expression.');
   });
+
+  it('test function', () => {
+    const pattern = new Pattern('posts/:id');
+
+    pattern.test('/posts/89').should.eql(true);
+    pattern.test('/post/89').should.eql(false);
+  });
+
 });
diff --git a/test/permalink.spec.js b/test/permalink.spec.js
index b84d14a2..d30b5db4 100644
--- a/test/permalink.spec.js
+++ b/test/permalink.spec.js
@@ -19,6 +19,18 @@ describe('Permalink', () => {
     permalink.regex.should.eql(/^(.+?)_(.+?)_(.+?)_(.+?)$/);
     permalink.params.should.eql(['year', 'i_month', 'i_day', 'title']);
 
+    permalink = new Permalink(':year/:month/:day/:title', {
+      segments: {
+        year: '(\\d{4})',
+        month: '(\\d{2})',
+        day: '(\\d{2})'
+      }
+    });
+
+    permalink.rule.should.eql(':year/:month/:day/:title');
+    permalink.regex.should.eql(/^(\d{4})\/(\d{2})\/(\d{2})\/(.+?)$/);
+    permalink.params.should.eql(['year', 'month', 'day', 'title']);
+
     permalink = new Permalink(':year/:month/:day/:title', {
       segments: {
         year: /(\d{4})/,
@@ -53,6 +65,7 @@ describe('Permalink', () => {
       day: '31',
       title: 'test'
     });
+    (typeof permalink.parse('test')).should.eql('undefined');
   });
 
   it('stringify()', () => {
diff --git a/test/spawn.spec.js b/test/spawn.spec.js
index 372f805a..0a6476b9 100644
--- a/test/spawn.spec.js
+++ b/test/spawn.spec.js
@@ -115,4 +115,11 @@ describe('spawn', () => {
   });
 
   it('stdio = inherit', () => spawn('echo', ['something'], { stdio: 'inherit' }));
+
+  it('exit with code', () => {
+    if (isWindows) {
+      return spawn('cmd.exe', ['/c', 'exit', '1'], { stdio: 'inherit' }).should.rejectedWith('Spawn failed');
+    }
+    return spawn('sh', ['/c', 'exit', '1'], { stdio: 'inherit' }).should.rejectedWith('Spawn failed');
+  });
 });
diff --git a/test/strip_indent.spec.js b/test/strip_indent.spec.js
new file mode 100644
index 00000000..90d3065b
--- /dev/null
+++ b/test/strip_indent.spec.js
@@ -0,0 +1,11 @@
+'use strict';
+
+const stripIndent = require('../dist/strip_indent');
+
+describe('stripIndent', () => {
+  it('default', () => {
+    const text = '\tunicorn\n\t\tcake';
+
+    stripIndent(text).should.eql('unicorn\n\tcake');
+  });
+});