feat: use different git command to get git branch name

lib/pact_broker/client/git.rb

@@ -18,8 +18,8 @@
 module PactBroker
   module Client
     module Git
-      COMMAND = 'git name-rev --name-only HEAD'.freeze
-      BRANCH_ENV_VAR_NAMES = %w{BUILDKITE_BRANCH CIRCLE_BRANCH TRAVIS_BRANCH GIT_BRANCH GIT_LOCAL_BRANCH APPVEYOR_REPO_BRANCH CI_COMMIT_REF_NAME}.freeze
+      COMMAND = 'git branch --remote --verbose --no-abbrev --contains'.freeze
+      BRANCH_ENV_VAR_names = %w{BUILDKITE_BRANCH CIRCLE_BRANCH TRAVIS_BRANCH GIT_BRANCH GIT_LOCAL_BRANCH APPVEYOR_REPO_BRANCH CI_COMMIT_REF_NAME}.freeze
 
       def self.branch
         find_branch_from_env_vars || branch_from_git_command
@@ -28,7 +28,7 @@ def self.branch
       # private
 
       def self.find_branch_from_env_vars
-        BRANCH_ENV_VAR_NAMES.collect { |env_var_name| branch_from_env_var(env_var_name) }.compact.first
+        BRANCH_ENV_VAR_names.collect { |env_var_name| branch_from_env_var(env_var_name) }.compact.first
       end
 
       def self.branch_from_env_var(env_var_name)
@@ -41,24 +41,32 @@ def self.branch_from_env_var(env_var_name)
       end
 
       def self.branch_from_git_command
-        branch_name = nil
+        branch_names = nil
         begin
-          branch_name = execute_git_command.strip
+          branch_names = execute_git_command
+            .split("\n")
+            .collect(&:strip)
+            .reject(&:empty?)
+            .collect(&:split)
+            .collect(&:first)
+            .collect{ |line| line.gsub(/^origin\//, '') }
+            .reject{ |line| line == "HEAD" }
+
         rescue StandardError => e
           raise PactBroker::Client::Error, "Could not determine current git branch using command `#{COMMAND}`. #{e.class} #{e.message}"
         end
 
-        validate_branch_name(branch_name)
-        branch_name
+        validate_branch_names(branch_names)
+        branch_names[0]
       end
 
-      def self.validate_branch_name(branch_name)
-        if !branch_name || branch_name.size == 0
-          raise PactBroker::Client::Error, "Command `#{COMMAND}` returned an empty string when trying to determine the git branch name. This is most likely not the value you want. You will need to get the branch name another way."
+      def self.validate_branch_names(branch_names)
+        if branch_names.size == 0
+          raise PactBroker::Client::Error, "Command `#{COMMAND}` didn't return anything that could be identified as the current branch."
         end
 
-        if branch_name == "HEAD"
-          raise PactBroker::Client::Error, "Command `#{COMMAND}` returned 'HEAD' when trying to determine the git branch name. This is probably because the repository is in detatched HEAD state. HEAD is most likely not the value you want. You will need to get the branch name another way."
+        if branch_names.size > 1
+          raise PactBroker::Client::Error, "Command `#{COMMAND}` returned multiple branches: #{branch_names.join(", ")}. You will need to get the branch name another way."
         end
       end
 

spec/lib/pact_broker/client/git_spec.rb

@@ -6,9 +6,6 @@ module Git
       describe ".branch" do
         before do
           allow(ENV).to receive(:[]).and_call_original
-          Git::BRANCH_ENV_VAR_NAMES.each do | env_var_name |
-            allow(ENV).to receive(:[]).with(env_var_name).and_return(nil)
-          end
         end
 
         subject { Git.branch }
@@ -30,23 +27,34 @@ module Git
           end
         end
 
-        context "when the git branch name comes back as HEAD" do
+        context "when one git branch name is returned (apart from HEAD)" do
+          before do
+            allow(Git).to receive(:execute_git_command).and_return(" origin/HEAD \n origin/foo")
+          end
+
+          it "raises an error" do
+            expect(subject).to eq "foo"
+          end
+        end
+
+        context "when two git branch names are returned (apart from HEAD)" do
           before do
-            allow(Git).to receive(:execute_git_command).and_return("HEAD")
+            allow(Git).to receive(:execute_git_command).and_return(" origin/HEAD \n origin/foo \n origin/bar")
           end
 
           it "raises an error" do
-            expect { subject }.to raise_error PactBroker::Client::Error, /returned 'HEAD'/
+            expect { subject }.to raise_error PactBroker::Client::Error, /returned multiple branches: foo, bar/
           end
         end
 
+
         context "when the git branch name comes back as an empty string" do
           before do
-            allow(Git).to receive(:execute_git_command).and_return("")
+            allow(Git).to receive(:execute_git_command).and_return(" origin/HEAD")
           end
 
           it "raises an error" do
-            expect { subject }.to raise_error PactBroker::Client::Error, /an empty string/
+            expect { subject }.to raise_error PactBroker::Client::Error, /didn't return anything/
           end
         end