refactor Git module to reduce duplication (#96)

lib/baes/git.rb

@@ -12,56 +12,31 @@ class GitError < StandardError; end
   class << self
     # checkout git branch and raise error on failure
     def checkout(branch_name)
-      stdout, stderr, status = Open3.capture3("git checkout #{branch_name}")
+      stdout = run_or_raise("git checkout #{branch_name}")
 
       output.puts(stdout)
-      output.puts(stderr) unless stderr.empty?
-
-      return if status.success?
-
-      raise GitError, "failed to rebase on '#{branch_name}'"
     end
 
     # rebase current branch on given branch name and return status
     def rebase(branch_name)
-      stdout, stderr, status = Open3.capture3("git rebase #{branch_name}")
-
-      output.puts(stdout)
-      output.puts(stderr) unless stderr.empty?
-
-      status
+      run_returning_status("git rebase #{branch_name}")
     end
 
     # get current branch name and raise on error
     def current_branch_name
-      stdout, stderr, status = Open3.capture3("git rev-parse --abbrev-ref HEAD")
-
-      output.puts(stderr) unless stderr.empty?
-
-      raise GitError, "failed to get current branch" unless status.success?
-
-      stdout.strip
+      run_or_raise("git rev-parse --abbrev-ref HEAD")
     end
 
     # list branch names and raise on failure
     def branch_names
-      stdout, stderr, status = Open3.capture3("git branch")
-
-      output.puts(stderr) unless stderr.empty?
-
-      raise GitError, "failed to get branches" unless status.success?
+      stdout = run_or_raise("git branch")
 
       stdout.lines.map { |line| line.sub(/^\*/, "").strip }
     end
 
     # skip current commit during rebase and return status
     def rebase_skip
-      stdout, stderr, status = Open3.capture3("git rebase --skip")
-
-      output.puts(stdout)
-      output.puts(stderr) unless stderr.empty?
-
-      status
+      run_returning_status("git rebase --skip")
     end
 
     # return the commit number the rebase is currently halted on
@@ -81,5 +56,28 @@ def last_rebase_step
         Integer(File.read("./.git/rebase-merge/end"))
       end
     end
+
+    private
+
+    def run_or_raise(command)
+      stdout, stderr, status = Open3.capture3(command)
+
+      unless status.success?
+        output.puts(stderr)
+
+        raise GitError, "failed to run '#{command}'"
+      end
+
+      stdout.strip
+    end
+
+    def run_returning_status(command)
+      stdout, stderr, status = Open3.capture3(command)
+
+      output.puts(stdout)
+      output.puts(stderr) unless stderr.empty?
+
+      status
+    end
   end
 end

spec/baes/git_spec.rb

@@ -9,6 +9,12 @@ def stub3(command, stdout: "", stderr: "", success: true)
     expect(Open3).to receive(:capture3).with(command).and_return(result)
   end
 
+  def run_and_rescue
+    yield
+  rescue StandardError
+    nil
+  end
+
   describe "#checkout" do
     it "prints stdout" do
       stub3("git checkout my_branch", stdout: "out")
@@ -18,19 +24,21 @@ def stub3(command, stdout: "", stderr: "", success: true)
       expect(output.string).to eq("out\n")
     end
 
-    it "prints stderr when present" do
-      stub3("git checkout my_branch", stdout: "out", stderr: "error")
+    context "when command is not successful" do
+      it "prints stdout and stderr" do
+        stub3("git checkout my_branch", stderr: "error", success: false)
 
-      described_class.checkout("my_branch")
+        run_and_rescue { described_class.checkout("my_branch") }
 
-      expect(output.string).to eq("out\nerror\n")
-    end
+        expect(output.string).to eq("error\n")
+      end
 
-    it "raises an error when command is not successful" do
-      stub3("git checkout my_branch", success: false)
+      it "raises an error" do
+        stub3("git checkout my_branch", success: false)
 
-      expect { described_class.checkout("my_branch") }
-        .to raise_error("failed to rebase on 'my_branch'")
+        expect { described_class.checkout("my_branch") }
+          .to raise_error("failed to run 'git checkout my_branch'")
+      end
     end
   end
 
@@ -61,19 +69,22 @@ def stub3(command, stdout: "", stderr: "", success: true)
   end
 
   describe "#current_branch_name" do
-    it "prints stderr when present" do
-      stub3("git rev-parse --abbrev-ref HEAD", stderr: "error")
+    context "when command is not successful" do
+      it "prints stderr" do
+        command = "git rev-parse --abbrev-ref HEAD"
+        stub3(command, stderr: "error", success: false)
 
-      described_class.current_branch_name
+        run_and_rescue { described_class.current_branch_name }
 
-      expect(output.string).to eq("error\n")
-    end
+        expect(output.string).to eq("error\n")
+      end
 
-    it "raises an error when status is not success" do
-      stub3("git rev-parse --abbrev-ref HEAD", success: false)
+      it "raises an error" do
+        stub3("git rev-parse --abbrev-ref HEAD", success: false)
 
-      expect { described_class.current_branch_name }
-        .to raise_error("failed to get current branch")
+        expect { described_class.current_branch_name }
+          .to raise_error("failed to run 'git rev-parse --abbrev-ref HEAD'")
+      end
     end
 
     it "returns the current branch name from stdout" do
@@ -86,19 +97,21 @@ def stub3(command, stdout: "", stderr: "", success: true)
   end
 
   describe "#branch_names" do
-    it "prints stderr when present" do
-      stub3("git branch", stdout: "out", stderr: "error")
+    context "when command is not successful" do
+      it "prints stderr" do
+        stub3("git branch", stderr: "error", success: false)
 
-      described_class.branch_names
+        run_and_rescue { described_class.branch_names }
 
-      expect(output.string).to eq("error\n")
-    end
+        expect(output.string).to eq("error\n")
+      end
 
-    it "raises an error when status is not success" do
-      stub3("git branch", success: false)
+      it "raises an error when status is not success" do
+        stub3("git branch", success: false)
 
-      expect { described_class.branch_names }
-        .to raise_error("failed to get branches")
+        expect { described_class.branch_names }
+          .to raise_error("failed to run 'git branch'")
+      end
     end
 
     it "returns the list of branches from stdout" do