diff --git a/git.gemspec b/git.gemspec
index 50b9c140..3d6b883f 100644
--- a/git.gemspec
+++ b/git.gemspec
@@ -32,6 +32,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'bump', '~> 0.10'
   s.add_development_dependency 'create_github_release', '~> 0.2'
   s.add_development_dependency 'minitar', '~> 0.9'
+  s.add_development_dependency 'mocha', '~> 2.1'
   s.add_development_dependency 'rake', '~> 13.0'
   s.add_development_dependency 'test-unit', '~> 3.3'
 
diff --git a/lib/git/lib.rb b/lib/git/lib.rb
index 1b586f60..335b45b6 100644
--- a/lib/git/lib.rb
+++ b/lib/git/lib.rb
@@ -1043,7 +1043,7 @@ def commit_tree(tree, opts = {})
       arr_opts = []
       arr_opts << tree
       arr_opts << '-p' << opts[:parent] if opts[:parent]
-      arr_opts += [opts[:parents]].map { |p| ['-p', p] }.flatten if opts[:parents]
+      arr_opts += Array(opts[:parents]).map { |p| ['-p', p] }.flatten if opts[:parents]
       command('commit-tree', *arr_opts, redirect: "< #{escape t.path}")
     end
 
@@ -1113,7 +1113,7 @@ def current_command_version
     # @example
     #   lib.current_command_version #=> [2, 42, 0]
     #
-    #   lib.compare_version_to(2, 41, 0) #=> 1 
+    #   lib.compare_version_to(2, 41, 0) #=> 1
     #   lib.compare_version_to(2, 42, 0) #=> 0
     #   lib.compare_version_to(2, 43, 0) #=> -1
     #
diff --git a/tests/test_helper.rb b/tests/test_helper.rb
index 79c06387..9bf44d6b 100644
--- a/tests/test_helper.rb
+++ b/tests/test_helper.rb
@@ -2,6 +2,7 @@
 require 'fileutils'
 require 'minitar'
 require 'test/unit'
+require 'mocha/test_unit'
 require 'tmpdir'
 
 require "git"
@@ -148,6 +149,7 @@ def with_custom_env_variables(&block)
   # @param expected_command_line [Array<String>] The expected arguments to be sent to Git::Lib#command
   # @param git_cmd [Symbol] the method to be called on the Git::Base object
   # @param git_cmd_args [Array<Object>] The arguments to be sent to the git_cmd method
+  # @param git_output [String] The output to be returned by the Git::Lib#command method
   #
   # @yield [git] An initialization block
   #   The initialization block is called after a test project is created with Git.init.
@@ -157,9 +159,11 @@ def with_custom_env_variables(&block)
   #
   # @return [void]
   #
-  def assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  def assert_command_line(expected_command_line, git_cmd, git_cmd_args, git_output = nil)
     actual_command_line = nil
 
+    command_output = ''
+
     in_temp_dir do |path|
       git = Git.init('test_project')
 
@@ -169,17 +173,26 @@ def assert_command_line(expected_command_line, git_cmd, git_cmd_args)
         # Mock the Git::Lib#command method to capture the actual command line args
         git.lib.define_singleton_method(:command) do |cmd, *opts, &block|
           actual_command_line = [cmd, *opts.flatten]
+          git_output
         end
 
-        git.send(git_cmd, *git_cmd_args)
+        command_output = git.send(git_cmd, *git_cmd_args)
       end
     end
 
     assert_equal(expected_command_line, actual_command_line)
+
+    command_output
   end
 
   def assert_child_process_success(&block)
     yield
     assert_equal 0, $CHILD_STATUS.exitstatus, "Child process failed with exitstatus #{$CHILD_STATUS.exitstatus}"
   end
+
+  def windows_platform?
+    # Check if on Windows via RUBY_PLATFORM (CRuby) and RUBY_DESCRIPTION (JRuby)
+    win_platform_regex = /mingw|mswin/
+    RUBY_PLATFORM =~ win_platform_regex || RUBY_DESCRIPTION =~ win_platform_regex
+  end
 end
diff --git a/tests/units/test_tree_ops.rb b/tests/units/test_tree_ops.rb
index 1f38cae9..02d0b43a 100644
--- a/tests/units/test_tree_ops.rb
+++ b/tests/units/test_tree_ops.rb
@@ -5,113 +5,237 @@
 class TestTreeOps < Test::Unit::TestCase
 
   def test_read_tree
-    in_bare_repo_clone do |g|
-      g.branch('testbranch1').in_branch('tb commit 1') do
-        new_file('test-file1', 'blahblahblah2')
-        g.add
-        true
-      end
-
-      g.branch('testbranch2').in_branch('tb commit 2') do
-        new_file('test-file2', 'blahblahblah3')
-        g.add
-        true
-      end
-
-      g.branch('testbranch3').in_branch('tb commit 3') do
-        new_file('test-file3', 'blahblahblah4')
-        g.add
-        true
-      end
-
-      # test some read-trees
-      tr = g.with_temp_index do
-        g.read_tree('testbranch1')
-        g.read_tree('testbranch2', :prefix => 'b2/')
-        g.read_tree('testbranch3', :prefix => 'b2/b3/')
-        index = g.ls_files
-        assert(index['b2/test-file2'])
-        assert(index['b2/b3/test-file3'])
-        g.write_tree
-      end
-
-      assert_equal('2423ef1b38b3a140bbebf625ba024189c872e08b', tr)
-
-      # only prefixed read-trees
-      tr = g.with_temp_index do
-        g.add  # add whats in our working tree
-        g.read_tree('testbranch1', :prefix => 'b1/')
-        g.read_tree('testbranch3', :prefix => 'b2/b3/')
-        index = g.ls_files
-        assert(index['example.txt'])
-        assert(index['b1/test-file1'])
-        assert(!index['b2/test-file2'])
-        assert(index['b2/b3/test-file3'])
-        g.write_tree
-      end
-
-      assert_equal('aa7349e1cdaf4b85cc6a6a0cf4f9b3f24879fa42', tr)
-
-      # new working directory too
-      tr = nil
-      g.with_temp_working do
-        tr = g.with_temp_index do
-          begin
-            g.add
-          rescue Exception => e
-            # Adding nothig is now validd on Git 1.7.x
-            # If an error ocurres (Git 1.6.x) it MUST raise Git::FailedError
-            assert_equal(e.class, Git::FailedError)
-          end
-          g.read_tree('testbranch1', :prefix => 'b1/')
-          g.read_tree('testbranch3', :prefix => 'b1/b3/')
-          index = g.ls_files
-          assert(!index['example.txt'])
-          assert(index['b1/test-file1'])
-          assert(!index['b2/test-file2'])
-          assert(index['b1/b3/test-file3'])
-          g.write_tree
-        end
-        assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', tr)
-      end
-
-      c = g.commit_tree(tr, :parents => 'HEAD')
-      assert(c.commit?)
-      assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', c.gtree.sha)
-
-      tmp = Tempfile.new('tesxt')
-      tmppath = tmp.path
-      tmp.close
-      tmp.unlink
-
-      g.with_index(tmppath) do
-        g.read_tree('testbranch1', :prefix => 'b1/')
-        g.read_tree('testbranch3', :prefix => 'b3/')
-        index = g.ls_files
-        assert(!index['b2/test-file2'])
-        assert(index['b3/test-file3'])
-        g.commit('hi')
-      end
-
-      assert(c.commit?)
-
-      files = g.ls_files
-      assert(!files['b1/example.txt'])
-
-      g.branch('newbranch').update_ref(c)
-      g.checkout('newbranch')
-      assert(!files['b1/example.txt'])
-
-      assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', c.gtree.sha)
-
-      g.with_temp_working do
-        assert(!File.directory?('b1'))
-        g.checkout_index
-        assert(!File.directory?('b1'))
-        g.checkout_index(:all => true)
-        assert(File.directory?('b1'))
-      end
-
-    end
+    treeish = 'testbranch1'
+    expected_command_line = ['read-tree', treeish]
+    git_cmd = :read_tree
+    git_cmd_args = [treeish]
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
   end
+
+  def test_read_tree_with_prefix
+    treeish = 'testbranch1'
+    prefix = 'foo'
+    expected_command_line = ['read-tree', "--prefix=#{prefix}", treeish]
+    git_cmd = :read_tree
+    git_cmd_args = [treeish, prefix: prefix]
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  def test_write_tree
+    expected_command_line = ['write-tree']
+    git_cmd = :write_tree
+    git_cmd_args = []
+    git_output = 'aa7349e'
+    result = assert_command_line(expected_command_line, git_cmd, git_cmd_args, git_output)
+    # the git output should be returned from Git::Base#write_tree
+    assert_equal(git_output, result)
+  end
+
+  def test_commit_tree_with_default_message
+    tree = 'tree-ref'
+
+    expected_message = 'commit tree tree-ref'
+    tempfile_path = 'foo'
+    mock_tempfile = mock('tempfile')
+    Tempfile.stubs(:new).returns(mock_tempfile)
+    mock_tempfile.stubs(:path).returns(tempfile_path)
+    mock_tempfile.expects(:write).with(expected_message)
+    mock_tempfile.expects(:close)
+
+    redirect_value = windows_platform? ? "< \"#{tempfile_path}\"" : "< '#{tempfile_path}'"
+
+    expected_command_line = ['commit-tree', tree, redirect: redirect_value]
+    git_cmd = :commit_tree
+    git_cmd_args = [tree]
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  def test_commit_tree_with_message
+    tree = 'tree-ref'
+    message = 'this is my message'
+
+    tempfile_path = 'foo'
+    mock_tempfile = mock('tempfile')
+    Tempfile.stubs(:new).returns(mock_tempfile)
+    mock_tempfile.stubs(:path).returns(tempfile_path)
+    mock_tempfile.expects(:write).with(message)
+    mock_tempfile.expects(:close)
+
+    redirect_value = windows_platform? ? "< \"#{tempfile_path}\"" : "< '#{tempfile_path}'"
+
+    expected_command_line = ['commit-tree', tree, redirect: redirect_value]
+    git_cmd = :commit_tree
+    git_cmd_args = [tree, message: message]
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  def test_commit_tree_with_parent
+    tree = 'tree-ref'
+    message = 'this is my message'
+    parent = 'parent-commit'
+
+    tempfile_path = 'foo'
+    mock_tempfile = mock('tempfile')
+    Tempfile.stubs(:new).returns(mock_tempfile)
+    mock_tempfile.stubs(:path).returns(tempfile_path)
+    mock_tempfile.expects(:write).with(message)
+    mock_tempfile.expects(:close)
+
+    redirect_value = windows_platform? ? "< \"#{tempfile_path}\"" : "< '#{tempfile_path}'"
+
+    expected_command_line = ['commit-tree', tree, "-p", parent, redirect: redirect_value]
+    git_cmd = :commit_tree
+    git_cmd_args = [tree, parent: parent, message: message]
+
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  def test_commit_tree_with_parents
+    tree = 'tree-ref'
+    message = 'this is my message'
+    parents = 'commit1'
+
+    tempfile_path = 'foo'
+    mock_tempfile = mock('tempfile')
+    Tempfile.stubs(:new).returns(mock_tempfile)
+    mock_tempfile.stubs(:path).returns(tempfile_path)
+    mock_tempfile.expects(:write).with(message)
+    mock_tempfile.expects(:close)
+
+    redirect_value = windows_platform? ? "< \"#{tempfile_path}\"" : "< '#{tempfile_path}'"
+
+    expected_command_line = ['commit-tree', tree, '-p', 'commit1', redirect: redirect_value]
+    git_cmd = :commit_tree
+    git_cmd_args = [tree, parents: parents, message: message]
+
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  def test_commit_tree_with_multiple_parents
+    tree = 'tree-ref'
+    message = 'this is my message'
+    parents = ['commit1', 'commit2']
+
+    tempfile_path = 'foo'
+    mock_tempfile = mock('tempfile')
+    Tempfile.stubs(:new).returns(mock_tempfile)
+    mock_tempfile.stubs(:path).returns(tempfile_path)
+    mock_tempfile.expects(:write).with(message)
+    mock_tempfile.expects(:close)
+
+    redirect_value = windows_platform? ? "< \"#{tempfile_path}\"" : "< '#{tempfile_path}'"
+
+    expected_command_line = ['commit-tree', tree, '-p', 'commit1', '-p', 'commit2', redirect: redirect_value]
+    git_cmd = :commit_tree
+    git_cmd_args = [tree, parents: parents, message: message]
+
+    assert_command_line(expected_command_line, git_cmd, git_cmd_args)
+  end
+
+  # Examples of how to use Git::Base#commit_tree, write_tree, and commit_tree
+  #
+  # def test_tree_ops
+  #   in_bare_repo_clone do |g|
+  #     g.branch('testbranch1').in_branch('tb commit 1') do
+  #       new_file('test-file1', 'blahblahblah2')
+  #       g.add
+  #       true
+  #     end
+  #
+  #     g.branch('testbranch2').in_branch('tb commit 2') do
+  #       new_file('test-file2', 'blahblahblah3')
+  #       g.add
+  #       true
+  #     end
+  #
+  #     g.branch('testbranch3').in_branch('tb commit 3') do
+  #       new_file('test-file3', 'blahblahblah4')
+  #       g.add
+  #       true
+  #     end
+  #
+  #     # test some read-trees
+  #     tr = g.with_temp_index do
+  #       g.read_tree('testbranch1')
+  #       g.read_tree('testbranch2', :prefix => 'b2/')
+  #       g.read_tree('testbranch3', :prefix => 'b2/b3/')
+  #       index = g.ls_files
+  #       assert(index['b2/test-file2'])
+  #       assert(index['b2/b3/test-file3'])
+  #       g.write_tree
+  #     end
+  #
+  #     assert_equal('2423ef1b38b3a140bbebf625ba024189c872e08b', tr)
+  #
+  #     # only prefixed read-trees
+  #     tr = g.with_temp_index do
+  #       g.add  # add whats in our working tree
+  #       g.read_tree('testbranch1', :prefix => 'b1/')
+  #       g.read_tree('testbranch3', :prefix => 'b2/b3/')
+  #       index = g.ls_files
+  #       assert(index['example.txt'])
+  #       assert(index['b1/test-file1'])
+  #       assert(!index['b2/test-file2'])
+  #       assert(index['b2/b3/test-file3'])
+  #       g.write_tree
+  #     end
+  #
+  #     assert_equal('aa7349e1cdaf4b85cc6a6a0cf4f9b3f24879fa42', tr)
+  #
+  #     # new working directory too
+  #     tr = nil
+  #     g.with_temp_working do
+  #       tr = g.with_temp_index do
+  #         begin
+  #           g.add
+  #         rescue Exception => e
+  #           # Adding nothig is now validd on Git 1.7.x
+  #           # If an error ocurres (Git 1.6.x) it MUST raise Git::FailedError
+  #           assert_equal(e.class, Git::FailedError)
+  #         end
+  #         g.read_tree('testbranch1', :prefix => 'b1/')
+  #         g.read_tree('testbranch3', :prefix => 'b1/b3/')
+  #         index = g.ls_files
+  #         assert(!index['example.txt'])
+  #         assert(index['b1/test-file1'])
+  #         assert(!index['b2/test-file2'])
+  #         assert(index['b1/b3/test-file3'])
+  #         g.write_tree
+  #       end
+  #       assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', tr)
+  #     end
+  #
+  #     c = g.commit_tree(tr, :parents => 'HEAD')
+  #     assert(c.commit?)
+  #     assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', c.gtree.sha)
+  #
+  #     g.with_temp_index do
+  #       g.read_tree('testbranch1', :prefix => 'b1/')
+  #       g.read_tree('testbranch3', :prefix => 'b3/')
+  #       index = g.ls_files
+  #       assert(!index['b2/test-file2'])
+  #       assert(index['b3/test-file3'])
+  #       g.commit('hi')
+  #     end
+  #
+  #     assert(c.commit?)
+  #
+  #     files = g.ls_files
+  #     assert(!files['b1/example.txt'])
+  #
+  #     g.branch('newbranch').update_ref(c)
+  #     g.checkout('newbranch')
+  #     assert(!files['b1/example.txt'])
+  #
+  #     assert_equal('b40f7a9072cdec637725700668f8fdebe39e6d38', c.gtree.sha)
+  #
+  #     g.with_temp_working do
+  #       assert(!File.directory?('b1'))
+  #       g.checkout_index
+  #       assert(!File.directory?('b1'))
+  #       g.checkout_index(:all => true)
+  #       assert(File.directory?('b1'))
+  #     end
+  #   end
+  # end
 end