Add `brew release-notes` developer command.

Outputs the merged pull requests on Homebrew/brew between two Git refs.

1 files changed, 43 insertions, 0 deletions

diff --git a/Library/Homebrew/dev-cmd/release-notes.rb b/Library/Homebrew/dev-cmd/release-notes.rb
new file mode 100644
index 000000000..919243764
--- /dev/null
+++ b/Library/Homebrew/dev-cmd/release-notes.rb
@@ -0,0 +1,43 @@
+#:  * `release-notes` [<previous_tag>] [<end_ref>]:
+#:    Output the merged pull requests on Homebrew/brew between two Git refs.
+#:    If no `previous_tag` is provided it defaults to the newest tag.
+#:    If no `end_ref` is provided it defaults to `origin/master`.
+#:
+#:    If `--markdown` is passed, output as a Markdown list.
+
+module Homebrew
+  module_function
+
+  def release_notes
+    previous_tag = ARGV.named.first
+    unless previous_tag
+      previous_tag = Utils.popen_read("git tag --list --sort=-version:refname")
+                          .lines.first.chomp
+    end
+    odie "Could not find any previous tags!" unless previous_tag
+
+    end_ref = ARGV.named[1] || "origin/master"
+
+    [previous_tag, end_ref].each do |ref|
+      next if quiet_system "git", "rev-parse", "--verify", "--quiet", ref
+      odie "Ref #{ref} does not exist!"
+    end
+
+    output = Utils.popen_read("git log --pretty=format:'%s >> - %b%n' '#{previous_tag}'..'#{end_ref}'")
+                  .lines.grep(/Merge pull request/)
+
+    output.map! do |s|
+      s.gsub(/.*Merge pull request #(\d+)[^>]*(>>)*/,
+             "https://github.com/Homebrew/brew/pull/\\1")
+    end
+    if ARGV.include?("--markdown")
+      output.map! do |s|
+        /(.*\d)+ - (.*)/ =~ s
+        "- [#{$2}](#{$1})"
+      end
+    end
+
+    puts "Release notes between #{previous_tag} and #{end_ref}:"
+    puts output
+  end
+end