diff --git a/test.js b/test.js
index a801441de..ff810695d 100644
--- a/test.js
+++ b/test.js
@@ -6,6 +6,7 @@ var shell = require('shelljs')
 var fs = require('fs')
 var path = require('path')
 var cliPath = path.resolve(__dirname, './index.js')
+var PATH
 
 require('chai').should()
 
@@ -13,6 +14,19 @@ function commit (msg) {
   shell.exec('git commit --allow-empty -m"' + msg + '"')
 }
 
+function writePackageJson (version) {
+  fs.writeFileSync('package.json', JSON.stringify({
+    version: version
+  }), 'utf-8')
+}
+
+function mockGit (logic) {
+  fs.writeFileSync('git', '#!/usr/bin/env node\n' + logic, 'utf8')
+  shell.chmod('+x', 'git')
+  PATH = shell.env.PATH
+  shell.env.PATH = shell.pwd() + ':' + PATH
+}
+
 describe('cli', function () {
   beforeEach(function () {
     shell.rm('-rf', 'tmp')
@@ -24,15 +38,17 @@ describe('cli', function () {
   })
 
   afterEach(function () {
+    if (PATH) {
+      shell.env['PATH'] = PATH
+      PATH = undefined
+    }
     shell.cd('../')
     shell.rm('-rf', 'tmp')
   })
 
   describe('CHANGELOG.md does not exist', function () {
     it('populates changelog with commits since last tag by default', function () {
-      fs.writeFileSync('package.json', JSON.stringify({
-        version: '1.0.0'
-      }), 'utf-8')
+      writePackageJson('1.0.0')
 
       commit('feat: first commit')
       shell.exec('git tag -a v1.0.0 -m "my awesome first release"')
@@ -46,9 +62,7 @@ describe('cli', function () {
     })
 
     it('includes all commits if --first-release is true', function () {
-      fs.writeFileSync('package.json', JSON.stringify({
-        version: '1.0.1'
-      }), 'utf-8')
+      writePackageJson('1.0.1')
 
       commit('feat: first commit')
       commit('fix: patch release')
@@ -63,9 +77,7 @@ describe('cli', function () {
 
   describe('CHANGELOG.md exists', function () {
     it('appends the new release above the last release, removing the old header', function () {
-      fs.writeFileSync('package.json', JSON.stringify({
-        version: '1.0.0'
-      }), 'utf-8')
+      writePackageJson('1.0.0')
       fs.writeFileSync('CHANGELOG.md', 'legacy header format<a name="1.0.0">\n', 'utf-8')
 
       commit('feat: first commit')
@@ -79,24 +91,44 @@ describe('cli', function () {
     })
   })
 
-  it('respects the --sign option', function () {
-    fs.writeFileSync('package.json', JSON.stringify({
-      version: '1.0.0'
-    }), 'utf-8')
+  describe('with mocked git', function () {
+    it('--sign signs the commit and tag', function () {
+      // mock git with file that writes args to gitcapture.log
+      mockGit('require("fs").appendFileSync("gitcapture.log", JSON.stringify(process.argv.splice(2)) + "\\n", "utf8")')
+      writePackageJson('1.0.0')
 
-    commit('feat: first commit')
+      shell.exec(cliPath + ' --sign').code.should.equal(0)
+
+      var captured = shell.cat('gitcapture.log').stdout.split('\n').map(function (line) {
+        return line ? JSON.parse(line) : line
+      })
+      captured[captured.length - 3].should.deep.equal(['commit', '-S', 'package.json', 'CHANGELOG.md', '-m', 'chore(release): 1.0.1'])
+      captured[captured.length - 2].should.deep.equal(['tag', '-s', 'v1.0.1', '-m', 'chore(release): 1.0.1'])
+    })
+
+    it('exits with error code if git commit fails', function () {
+      // mock git by throwing on attempt to commit
+      mockGit('if (process.argv[2] === "commit") { console.error("commit yourself"); process.exit(128); }')
+      writePackageJson('1.0.0')
+
+      var result = shell.exec(cliPath)
+      result.code.should.equal(1)
+      result.stdout.should.match(/commit yourself/)
+    })
+
+    it('exits with error code if git tag fails', function () {
+      // mock git by throwing on attempt to commit
+      mockGit('if (process.argv[2] === "tag") { console.error("tag, you\'re it"); process.exit(128); }')
+      writePackageJson('1.0.0')
 
-    // this should fail without a GPG key
-    var result = shell.exec(cliPath + ' --sign')
-    result.code.should.equal(1)
-    result.stdout.should.match(/gpg\: signing failed\: secret key not available/)
-    result.stdout.should.match(/error\: gpg failed to sign the data/)
+      var result = shell.exec(cliPath)
+      result.code.should.equal(1)
+      result.stdout.should.match(/tag, you're it/)
+    })
   })
 
   it('handles commit messages longer than 80 characters', function () {
-    fs.writeFileSync('package.json', JSON.stringify({
-      version: '1.0.0'
-    }), 'utf-8')
+    writePackageJson('1.0.0')
 
     commit('feat: first commit')
     shell.exec('git tag -a v1.0.0 -m "my awesome first release"')
@@ -109,9 +141,7 @@ describe('cli', function () {
   })
 
   it('formats the commit and tag messages appropriately', function () {
-    fs.writeFileSync('package.json', JSON.stringify({
-      version: '1.0.0'
-    }), 'utf-8')
+    writePackageJson('1.0.0')
 
     commit('feat: first commit')
     shell.exec('git tag -a v1.0.0 -m "my awesome first release"')