Implement rev_parse method and enhance diff command to resolve git refs

Author: andrew

CHANGELOG.md

@@ -1,6 +1,12 @@
 ## [Unreleased]
 
+## [0.1.1] - 2026-01-01
+
 - `git pkgs history` now works without a package argument to show all dependency changes
+- `git pkgs diff` supports git refs (HEAD~10, branch names, tags) not just SHAs
+- `git pkgs diff` lazily inserts commits not found in the database
+- Expanded manifest file pattern matching for all supported ecosystems
+- Switched to ecosystems-bibliothecary
 
 ## [0.1.0] - 2026-01-01
 

README.md

@@ -28,6 +28,7 @@ git pkgs history        # all dependency changes over time
 git pkgs history rails  # track a specific package
 git pkgs why rails      # why was this added?
 git pkgs diff --from=HEAD~10  # what changed recently?
+git pkgs diff --from=main --to=feature  # compare branches
 ```
 
 ## Commands

lib/git/pkgs/commands/diff.rb

@@ -19,26 +19,38 @@ def run
 
           Database.connect(repo.git_dir)
 
-          from_sha = @options[:from]
-          to_sha = @options[:to] || repo.head_sha
+          from_ref = @options[:from]
+          to_ref = @options[:to] || "HEAD"
+
+          unless from_ref
+            $stderr.puts "Usage: git pkgs diff --from=REF [--to=REF]"
+            exit 1
+          end
+
+          # Resolve git refs (like HEAD~10) to SHAs
+          from_sha = repo.rev_parse(from_ref)
+          to_sha = repo.rev_parse(to_ref)
 
           unless from_sha
-            $stderr.puts "Usage: git pkgs diff --from=SHA [--to=SHA]"
+            $stderr.puts "Could not resolve '#{from_ref}'"
             exit 1
           end
 
-          from_commit = Models::Commit.find_by(sha: from_sha) ||
-                        Models::Commit.where("sha LIKE ?", "#{from_sha}%").first
-          to_commit = Models::Commit.find_by(sha: to_sha) ||
-                      Models::Commit.where("sha LIKE ?", "#{to_sha}%").first
+          unless to_sha
+            $stderr.puts "Could not resolve '#{to_ref}'"
+            exit 1
+          end
+
+          from_commit = find_or_create_commit(repo, from_sha)
+          to_commit = find_or_create_commit(repo, to_sha)
 
           unless from_commit
-            $stderr.puts "Commit '#{from_sha}' not found in database"
+            $stderr.puts "Commit '#{from_sha[0..7]}' not found"
             exit 1
           end
 
           unless to_commit
-            $stderr.puts "Commit '#{to_sha}' not found in database"
+            $stderr.puts "Commit '#{to_sha[0..7]}' not found"
             exit 1
           end
 
@@ -98,17 +110,38 @@ def run
           puts "Summary: +#{added.map(&:name).uniq.count} -#{removed.map(&:name).uniq.count} ~#{modified.map(&:name).uniq.count}"
         end
 
+        def find_or_create_commit(repo, sha)
+          commit = Models::Commit.find_by(sha: sha) ||
+                   Models::Commit.where("sha LIKE ?", "#{sha}%").first
+          return commit if commit
+
+          # Lazily insert commit if it exists in git but not in database
+          rugged_commit = repo.lookup(sha)
+          return nil unless rugged_commit
+
+          Models::Commit.create!(
+            sha: rugged_commit.oid,
+            message: rugged_commit.message,
+            author_name: rugged_commit.author[:name],
+            author_email: rugged_commit.author[:email],
+            committed_at: rugged_commit.time,
+            has_dependency_changes: false
+          )
+        rescue Rugged::OdbError
+          nil
+        end
+
         def parse_options
           options = {}
 
           parser = OptionParser.new do |opts|
-            opts.banner = "Usage: git pkgs diff --from=SHA [--to=SHA] [options]"
+            opts.banner = "Usage: git pkgs diff --from=REF [--to=REF] [options]"
 
-            opts.on("-f", "--from=SHA", "Start commit (required)") do |v|
+            opts.on("-f", "--from=REF", "Start commit (required)") do |v|
               options[:from] = v
             end
 
-            opts.on("-t", "--to=SHA", "End commit (default: HEAD)") do |v|
+            opts.on("-t", "--to=REF", "End commit (default: HEAD)") do |v|
               options[:to] = v
             end
 

lib/git/pkgs/repository.rb

@@ -120,6 +120,12 @@ def merge_commit?(rugged_commit)
       def head_sha
         @rugged.head.target_id
       end
+
+      def rev_parse(ref)
+        @rugged.rev_parse(ref).oid
+      rescue Rugged::ReferenceError, Rugged::InvalidError
+        nil
+      end
     end
   end
 end

lib/git/pkgs/version.rb

@@ -2,6 +2,6 @@
 
 module Git
   module Pkgs
-    VERSION = "0.1.0"
+    VERSION = "0.1.1"
   end
 end

test/git/pkgs/test_cli.rb

@@ -4,6 +4,8 @@
 require "stringio"
 
 class Git::Pkgs::TestCLI < Minitest::Test
+  include TestHelpers
+
   def test_help_command
     output = capture_stdout do
       Git::Pkgs::CLI.run(["help"])
@@ -49,3 +51,67 @@ def capture_stderr
     $stderr = original
   end
 end
+
+class Git::Pkgs::TestDiffCommand < Minitest::Test
+  include TestHelpers
+
+  def setup
+    create_test_repo
+    add_file("Gemfile", "source 'https://rubygems.org'\ngem 'rails'")
+    commit("Initial commit")
+    add_file("Gemfile", "source 'https://rubygems.org'\ngem 'rails'\ngem 'puma'")
+    commit("Add puma")
+    @git_dir = File.join(@test_dir, ".git")
+    Git::Pkgs::Database.connect(@git_dir)
+    Git::Pkgs::Database.create_schema
+  end
+
+  def teardown
+    cleanup_test_repo
+  end
+
+  def test_find_or_create_commit_finds_existing_commit
+    repo = Git::Pkgs::Repository.new(@test_dir)
+    sha = repo.head_sha
+
+    # Create commit in database first
+    Git::Pkgs::Models::Commit.create!(
+      sha: sha,
+      message: "Test",
+      author_name: "Test",
+      author_email: "test@example.com",
+      committed_at: Time.now
+    )
+
+    diff = Git::Pkgs::Commands::Diff.new([])
+    result = diff.send(:find_or_create_commit, repo, sha)
+
+    assert result
+    assert_equal sha, result.sha
+  end
+
+  def test_find_or_create_commit_creates_missing_commit
+    repo = Git::Pkgs::Repository.new(@test_dir)
+    sha = repo.head_sha
+
+    # Commit doesn't exist in database yet
+    assert_nil Git::Pkgs::Models::Commit.find_by(sha: sha)
+
+    diff = Git::Pkgs::Commands::Diff.new([])
+    result = diff.send(:find_or_create_commit, repo, sha)
+
+    assert result
+    assert_equal sha, result.sha
+    # Verify it was persisted
+    assert Git::Pkgs::Models::Commit.find_by(sha: sha)
+  end
+
+  def test_find_or_create_commit_returns_nil_for_invalid_sha
+    repo = Git::Pkgs::Repository.new(@test_dir)
+
+    diff = Git::Pkgs::Commands::Diff.new([])
+    result = diff.send(:find_or_create_commit, repo, "0000000000000000000000000000000000000000")
+
+    assert_nil result
+  end
+end

test/git/pkgs/test_repository.rb

@@ -66,4 +66,33 @@ def test_content_at_commit
 
     assert_equal "# Test", content
   end
+
+  def test_rev_parse_resolves_head
+    repo = Git::Pkgs::Repository.new(@test_dir)
+    sha = repo.rev_parse("HEAD")
+
+    assert sha
+    assert_equal 40, sha.length
+    assert_equal repo.head_sha, sha
+  end
+
+  def test_rev_parse_resolves_relative_refs
+    add_file("file1.txt", "content")
+    commit("Second commit")
+
+    repo = Git::Pkgs::Repository.new(@test_dir)
+    head_sha = repo.rev_parse("HEAD")
+    parent_sha = repo.rev_parse("HEAD~1")
+
+    assert head_sha
+    assert parent_sha
+    refute_equal head_sha, parent_sha
+  end
+
+  def test_rev_parse_returns_nil_for_invalid_ref
+    repo = Git::Pkgs::Repository.new(@test_dir)
+    sha = repo.rev_parse("nonexistent-ref")
+
+    assert_nil sha
+  end
 end