Support passing :head as a valid commit_id to Bob.build

lib/bob.rb

@@ -12,26 +12,40 @@
 module Bob
   # Builds the specified <tt>buildable</tt>. This object must understand
   # the API described in the README.
+  #
+  # The second argument will take an array of commit_ids, which should be
+  # strings with the relevant identifier (a SHA1 hash for git repositories,
+  # a numerical revision for svn repositories, etc).
+  #
+  # You can pass :head as a commit identifier to build the latest commit
+  # in the repo. Examples:
+  #
+  #     Bob.build(buildable, :head) # just build the head
+  #     Bob.build(buildable, ["4", "3", "2"]) # build revision 4, 3, and 2
+  #                                           # (in that order)
+  #     Bob.build(buildable, [:head, "a30fb12"]) # build the HEAD and a30fb12
+  #                                              # commits in this repo.
   def self.build(buildable, commit_ids)
     Array(commit_ids).each do |commit_id|
       Builder.new(buildable, commit_id).build
     end
   end
 
-  # Directory where the code for the different buildables will be checked out. Make sure
-  # the user running Bob is allowed to write to this directory.
+  # Directory where the code for the different buildables will be checked out.
+  # Make sure the user running Bob is allowed to write to this directory.
   def self.directory
     @directory || "/tmp"
   end
 
-  # What will you use to build in background. Must respond to <tt>call</tt> and take a block
-  # which will be run "in background". The default is to run in foreground.
+  # What will you use to build in background. Must respond to <tt>call</tt> and
+  # take a block which will be run "in background". The default is to run in 
+  # foreground.
   def self.engine
     @engine || BackgroundEngines::Foreground
   end
 
-  # What to log with (must implement ruby's Logger interface). Logs to STDOUT by
-  # default.
+  # What to log with (must implement ruby's Logger interface). Logs to STDOUT 
+  # by default.
   def self.logger
     @logger || Logger.new(STDOUT)
   end

lib/bob/builder.rb

@@ -2,8 +2,14 @@ module Bob
   # A Builder will take care of building a buildable (wow, you didn't see that coming,
   # right?).
   class Builder
-    attr_reader :buildable, :commit_id
+    attr_reader :buildable
 
+    # Instantiate the Builder, passing an object that understands the <tt>Buildable</tt>
+    # interface, and a <tt>commit_id</tt>.
+    #
+    # You can pass <tt>:head</tt> as the commit id, in which case it will resolve to the
+    # head commit of the current branch (for example, "HEAD" under git, or the latest
+    # revision under svn)
     def initialize(buildable, commit_id)
       @buildable = buildable
       @commit_id = commit_id
@@ -28,6 +34,10 @@ def build
 
     private
 
+    def commit_id
+      @commit_id == :head ? scm.head : @commit_id
+    end
+
     def run_build_script
       build_output = nil
 

lib/bob/scm/abstract.rb

@@ -8,16 +8,17 @@ def initialize(uri, branch)
         @branch = branch
       end
 
-      # Checkout the code into <tt>working_dir</tt> at the specified revision and
-      # call the passed block
+      # Checkout the code into <tt>working_dir</tt> at the specified revision
+      # and call the passed block
       def with_commit(commit_id)
         update_code
         checkout(commit_id)
         yield
       end
 
-      # Directory where the code will be checked out. Make sure the user running Bob is
-      # allowed to write to this directory (or you'll get a <tt>Errno::EACCESS</tt>)
+      # Directory where the code will be checked out. Make sure the user 
+      # running Bob is allowed to write to this directory (or you'll get a 
+      # <tt>Errno::EACCESS</tt>)
       def working_dir
         @working_dir ||= "#{Bob.directory}/#{path_from_uri}".tap do |path|
           FileUtils.mkdir_p path
@@ -33,10 +34,17 @@ def info(commit_id)
         raise NotImplementedError
       end
 
+      # Return the identifier for the last commit in this branch of the
+      # repository.
+      def head
+        raise NotImplementedError
+      end
+
       protected
 
       def run(command, cd_into_working_dir=true)
-        command = "(#{cd_into_working_dir ? "cd #{working_dir} && " : ""}#{command} &>/dev/null)"
+        command_prefix = cd_into_working_dir ? "cd #{working_dir} && " : ""
+        command = "(#{command_prefix}#{command} &>/dev/null)"
         Bob.logger.debug command
         system(command) || raise(CantRunCommand, "Couldn't run SCM command `#{command}`")
       end

lib/bob/scm/git.rb

@@ -8,6 +8,10 @@ def info(commit_id)
         end
       end
 
+      def head
+        `git ls-remote --heads #{uri} #{branch} | cut -f1`.chomp
+      end
+
       protected
 
       def path_from_uri

lib/bob/scm/svn.rb

@@ -12,6 +12,11 @@ def info(revision)
           :committed_at => Time.parse(meta[2]) }
       end
 
+      def head
+        %x[svn info #{uri}].split("\n").detect {|line| line =~ /^Revision: (\d+)/ }
+        $1.to_s
+      end
+
       def with_commit(commit_id)
         update_code
         checkout(commit_id)

test/helper.rb

@@ -4,10 +4,17 @@
 
 begin
   require "redgreen"
-  require "ruby-debug"
 rescue LoadError
 end
 
+if ENV["DEBUG"]
+  require "ruby-debug"
+else
+  def debugger
+    puts "Run your tests with DEBUG=1 to use the debugger"
+  end
+end
+
 $LOAD_PATH.unshift(File.expand_path(File.dirname(__FILE__) + "/../lib"),
                    File.expand_path(File.dirname(__FILE__) + "/../test/helper"))
 

test/scm/git_test.rb

@@ -56,4 +56,17 @@ def setup
     assert_equal 2, buildable.metadata.length
     assert_equal 2, buildable.builds.length
   end
+
+  test "can build the head of a repository" do
+    repo.add_failing_commit
+    repo.add_successful_commit
+
+    buildable.build(:head)
+
+    assert_equal 1, buildable.builds.length
+
+    status, output = buildable.builds[repo.head]
+    assert_equal :successful,          status
+    assert_equal "Running tests...\n", output
+  end
 end

test/scm/svn_test.rb

@@ -54,4 +54,17 @@ def setup
     assert_equal 3, buildable.metadata.length
     assert_equal 3, buildable.builds.length
   end
+
+  test "can build the head of a repository" do
+    repo.add_failing_commit
+    repo.add_successful_commit
+
+    buildable.build(:head)
+
+    assert_equal 1, buildable.builds.length
+
+    status, output = buildable.builds["3"]
+    assert_equal :successful,          status
+    assert_equal "Running tests...\n", output
+  end
 end