Resolve sha in delta output for HEAD

CHANGELOG.md

@@ -1,3 +1,8 @@
+## [1.5.2] - 2024-10-21
+
+- Fixed bug where delta mode validations would fail when the commit was a non-sha value.
+- Allow HEAD as specified commit in delta mode
+
 ## [1.5.1] - 2024-10-15
 
 - Fix bug where worktree checkout silently failed

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    churn_vs_complexity (1.5.1)
+    churn_vs_complexity (1.5.2)
       flog (~> 4.8)
       git (~> 2.1)
 

README.md

@@ -49,9 +49,10 @@ Usage: churn_vs_complexity [options] folder
     -q, --quarter                    Calculate churn for the quarter leading up to the most recent commit
     -y, --year                       Calculate churn for the year leading up to the most recent commit
         --timetravel N               Calculate summary for all commits at intervals of N days throughout project history or from the date specified with --since
-        --delta SHA                  Identify changes between the specified commit and the previous commit and annotate changed files with complexity score. Can be used multiple times to specify multiple commits.
+        --delta SHA                  Identify changes between the specified commit (SHA) and the previous commit and annotate changed files with complexity score. SHA can be a full or short commit hash, or the value HEAD. Can be used multiple times to specify multiple commits.
         --dry-run                    Echo the chosen options from the CLI
     -h, --help                       Display help
+        --version                    Display version
 ```
 
 Note that when using the `--timetravel` mode, the semantics of some flags are subtly different from normal mode:

lib/churn_vs_complexity/cli/main.rb

@@ -11,6 +11,7 @@ def run!(options, folder)
           validate_options!(options)
           config = config(options)
           config.validate!
+
           config.checker.check(folder:)
         end
 

lib/churn_vs_complexity/cli/parser.rb

@@ -64,7 +64,7 @@ def self.create
           end
 
           opts.on('--delta SHA',
-                  'Identify changes between the specified commit and the previous commit and annotate changed files with complexity score. Can be used multiple times to specify multiple commits.',) do |value|
+                  'Identify changes between the specified commit (SHA) and the previous commit and annotate changed files with complexity score. SHA can be a full or short commit hash, or the value HEAD. Can be used multiple times to specify multiple commits.',) do |value|
             options[:mode] = :delta
             (options[:commits] ||= []) << value
           end

lib/churn_vs_complexity/delta.rb

@@ -6,6 +6,7 @@
 require_relative 'delta/factory'
 require_relative 'delta/complexity_annotator'
 require_relative 'delta/multi_checker'
+require_relative 'delta/commit_hydrator'
 
 module ChurnVsComplexity
   module Delta

lib/churn_vs_complexity/delta/checker.rb

@@ -40,12 +40,10 @@ def setup_worktree(folder:)
       end
 
       def commit_summary(folder:)
-        summary = { commit: @commit }
-        if @serializer.respond_to?(:has_commit_summary?) && @serializer.has_commit_summary?
-          parent, next_commit = @factory.git_strategy(folder:).surrounding(commit: @commit)
-          summary.merge!(parent:, next_commit:)
-        end
-        summary
+        CommitHydrator.new(
+          git_strategy: @factory.git_strategy(folder:),
+          serializer: @serializer,
+        ).hydrate(@commit)
       end
 
       def valid_commit?(folder:)

lib/churn_vs_complexity/delta/commit_hydrator.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module ChurnVsComplexity
+  module Delta
+    class CommitHydrator
+      def initialize(git_strategy:, serializer:)
+        @git_strategy = git_strategy
+        @serializer = serializer
+      end
+
+      def hydrate(commit_sha)
+        commit = @git_strategy.object(commit_sha)
+        summary = { commit: commit.sha }
+        if @serializer.respond_to?(:has_commit_summary?) && @serializer.has_commit_summary?
+          parent, next_commit = @git_strategy.surrounding(commit:)
+          summary.merge!(parent:, next_commit:)
+        end
+        summary
+      end
+    end
+  end
+end

lib/churn_vs_complexity/git_strategy.rb

@@ -14,13 +14,15 @@ def valid_commit?(commit:)
       false
     end
 
+    def object(commit)
+      commit.is_a?(Git::Object::Commit) ? commit : @repo.object(commit)
+    end
+
     def surrounding(commit:)
-      current = @repo.object(commit)
-      parent = current.parent
-      next_commit = @repo.log(100_000).find do |c|
-        c.parents.map(&:sha).include?(current.sha)
-      end
-      [parent&.sha, next_commit&.sha]
+      current = object(commit)
+      is_head = current.sha == @repo.object('HEAD').sha
+      next_commit = is_head ? nil : @repo.log(100_000).find { |c| c.parents.map(&:sha).include?(current.sha) }
+      [current.parent&.sha, next_commit&.sha]
     end
 
     def changes(commit:)

lib/churn_vs_complexity/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module ChurnVsComplexity
-  VERSION = '1.5.1'
+  VERSION = '1.5.2'
 end

test/churn_vs_complexity/delta/checker_test.rb

@@ -142,6 +142,10 @@ def changes(commit:)
         @changes
       end
 
+      def object(commit)
+        GitCommitStub.new(sha: commit)
+      end
+
       def surrounding(commit:)
         %w[aabbccdd bbbbccdd]
       end
@@ -166,6 +170,8 @@ def checkout(sha)
       def folder = FOLDER
     end
 
+    GitCommitStub = Data.define(:sha)
+
     class EngineStub
       def initialize(fail_to_process: false)
         @fail_to_process = fail_to_process

test/churn_vs_complexity/delta/commit_hydrator_test.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+module ChurnVsComplexity
+  module Delta
+    class CommitHydratorTest < TLDR
+      def test_resolves_sha_of_head_commit
+        expected_sha = '123abcde'
+        git_strategy = GitStrategyStub.new(object_sha: expected_sha)
+        hydrator = CommitHydrator.new(git_strategy:, serializer: nil)
+
+        result = hydrator.hydrate('HEAD')
+
+        assert_equal expected_sha, result[:commit]
+      end
+
+      GitCommitStub = Data.define(:sha)
+
+      class GitStrategyStub
+        def initialize(object_sha: nil)
+          @object_sha = object_sha
+        end
+
+        def object(commit)
+          GitCommitStub.new(sha: @object_sha || commit)
+        end
+      end
+    end
+  end
+end