fix: improve error message for Git::Lib#branches_all

jcouball · jcouball · commit 7646e38a1670 · 2024-11-19T11:58:09.000-08:00
When the output from `git branch -a` can not be parsed, return
an error that shows the complete output, the line containing the
error, and the line with the error.
diff --git a/lib/git/lib.rb b/lib/git/lib.rb
@@ -362,7 +362,7 @@ def name_rev(commit_ish)
     #
     # @example Get the contents of a file with a block
     #  lib.cat_file_contents('README.md') { |f| f.read } # => "This is a README file\n"
-    #  
+    #
     # @param object [String] the object whose contents to return
     #
     # @return [String] the object contents
@@ -641,10 +641,13 @@ def change_head_branch(branch_name)
     /x
 
     def branches_all
-      command_lines('branch', '-a').map do |line|
+      lines = command_lines('branch', '-a')
+      lines.each_with_index.map do |line, line_index|
         match_data = line.match(BRANCH_LINE_REGEXP)
-        raise Git::UnexpectedResultError, 'Unexpected branch line format' unless match_data
+
+        raise Git::UnexpectedResultError, unexpected_branch_line_error(lines, line, line_index) unless match_data
         next nil if match_data[:not_a_branch] || match_data[:detached_ref]
+
         [
           match_data[:refname],
           !match_data[:current].nil?,
@@ -654,6 +657,18 @@ def branches_all
       end.compact
     end
 
+    def unexpected_branch_line_error(lines, line, index)
+      <<~ERROR
+        Unexpected line in output from `git branch -a`, line #{index + 1}
+
+        Full output:
+          #{lines.join("\n  ")}
+
+        Line #{index + 1}:
+          "#{line}"
+      ERROR
+    end
+
     def worktrees_all
       arr = []
       directory = ''
diff --git a/tests/units/test_lib.rb b/tests/units/test_lib.rb
@@ -299,6 +299,39 @@ def test_branches_all
     assert(branches.select { |b| /master/.match(b[0]) }.size > 0)  # has a master branch
   end
 
+  test 'Git::Lib#branches_all with unexpected output from git branches -a' do
+    # Mock command lines to return unexpected branch data
+    def @lib.command_lines(*_command)
+      <<~COMMAND_LINES.split("\n")
+        * (HEAD detached at origin/master)
+          this line should result in a Git::UnexpectedResultError
+          master
+          remotes/origin/HEAD -> origin/master
+          remotes/origin/master
+      COMMAND_LINES
+    end
+
+    begin
+      branches = @lib.branches_all
+    rescue Git::UnexpectedResultError => e
+      assert_equal(<<~MESSAGE, e.message)
+        Unexpected line in output from `git branch -a`, line 2
+
+        Full output:
+          * (HEAD detached at origin/master)
+            this line should result in a Git::UnexpectedResultError
+            master
+            remotes/origin/HEAD -> origin/master
+            remotes/origin/master
+
+        Line 2:
+          "  this line should result in a Git::UnexpectedResultError"
+      MESSAGE
+    else
+      raise RuntimeError, 'Expected Git::UnexpectedResultError'
+    end
+  end
+
   def test_config_remote
     config = @lib.config_remote('working')
     assert_equal('../working.git', config['url'])
