extract: semver aware

Library/Homebrew/dev-cmd/extract.rb

@@ -125,24 +125,34 @@ def extract
     if args.version
       ohai "Searching repository history"
       version = args.version
-      rev = "HEAD"
+      version_segments = Gem::Version.new(version).segments if Gem::Version.correct?(version)
+      rev = nil
       test_formula = nil
       result = ""
       loop do
-        rev, (path,) = Git.last_revision_commit_of_files(repo, pattern, before_commit: "#{rev}~1")
+        rev = rev.nil? ? "HEAD" : "#{rev}~1"
+        rev, (path,) = Git.last_revision_commit_of_files(repo, pattern, before_commit: rev)
         odie "Could not find #{name}! The formula or version may not have existed." if rev.nil?
 
         file = repo/path
         result = Git.last_revision_of_file(repo, file, before_commit: rev)
         if result.empty?
-          odebug "Skipping revision #{rev} - file is empty at this revision" if ARGV.debug?
+          odebug "Skipping revision #{rev} - file is empty at this revision"
           next
         end
 
         test_formula = formula_at_revision(repo, name, file, rev)
         break if test_formula.nil? || test_formula.version == version
 
-        odebug "Trying #{test_formula.version} from revision #{rev} against desired #{version}" if ARGV.debug?
+        if version_segments && Gem::Version.correct?(test_formula.version)
+          test_formula_version_segments = Gem::Version.new(test_formula.version).segments
+          if version_segments.length < test_formula_version_segments.length
+            odebug "Apply semantic versioning with #{test_formual_version_segments}"
+            break if version_segments == test_formula_version_segments.first(version_segments.length)
+          end
+        end
+
+        odebug "Trying #{test_formula.version} from revision #{rev} against desired #{version}"
       end
       odie "Could not find #{name}! The formula or version may not have existed." if test_formula.nil?
     else
@@ -181,7 +191,7 @@ def extract
             brew extract --force --version=#{version} #{name} #{destination_tap.name}
         EOS
       end
-      odebug "Overwriting existing formula at #{path}" if ARGV.debug?
+      odebug "Overwriting existing formula at #{path}"
       path.delete
     end
     ohai "Writing formula for #{name} from revision #{rev} to #{path}"

Library/Homebrew/test/dev-cmd/extract_spec.rb

@@ -7,7 +7,7 @@
 end
 
 describe "brew extract", :integration_test do
-  it "retrieves the specified version of formula, defaulting to most recent" do
+  let!(:target) do
     path = Tap::TAP_DIRECTORY/"homebrew/homebrew-foo"
     (path/"Formula").mkpath
     target = Tap.from_path(path)
@@ -23,12 +23,27 @@
       system "git", "add", "--all"
       system "git", "commit", "-m", "testball 0.2"
     end
+    { name: target.name, path: path }
+  end
 
-    expect { brew "extract", "testball", target.name, "--version=0.1" }
+  it "retrieves the most recent version of formula" do
+    expect { brew "extract", "testball", target[:name] }
       .to be_a_success
+    expect(target[:path]/"Formula/testball@0.2.rb").to exist
+    expect(Formulary.factory(target[:path]/"Formula/testball@0.2.rb").version).to be == "0.2"
+  end
 
-    expect(path/"Formula/testball@0.1.rb").to exist
+  it "retrieves the specified version of formula" do
+    expect { brew "extract", "testball", target[:name], "--version=0.1" }
+      .to be_a_success
+    expect(target[:path]/"Formula/testball@0.1.rb").to exist
+    expect(Formulary.factory(target[:path]/"Formula/testball@0.1.rb").version).to be == "0.1"
+  end
 
-    expect(Formulary.factory(path/"Formula/testball@0.1.rb").version).to be == "0.1"
+  it "retrieves the compatible version of formula" do
+    expect { brew "extract", "testball", target[:name], "--version=0", "--debug" }
+      .to be_a_success
+    expect(target[:path]/"Formula/testball@0.rb").to exist
+    expect(Formulary.factory(target[:path]/"Formula/testball@0.rb").version).to be == "0.2"
   end
 end