Allow execution from scripts and GUI clients

If the Git hook is called from outside of a terminal, just fail on
errors without trying to ask the user for input.

This previously crashed because it assumed `/dev/tty` was present. This
isn't the case when called from a GUI like RubyMine.

Fixes #20

Author: Mike Foley

Diff for: lib/fit_commit/runner.rb

@@ -22,22 +22,30 @@ def run
       run_validators
       return EXIT_CODE_ALLOW_COMMIT if [errors, warnings].all?(&:empty?)
       print_results
+      allow_commit = errors.empty? || ask_force_commit
 
-      allow_commit = errors.empty?
-      unless allow_commit
-        stderr.print "\nForce commit? [y/n] "
-        return EXIT_CODE_REJECT_COMMIT unless stdin.gets =~ /y/i
-        allow_commit = true
+      if allow_commit
+        stderr.print "\n"
+        EXIT_CODE_ALLOW_COMMIT
+      else
+        EXIT_CODE_REJECT_COMMIT
       end
-
-      stderr.print "\n"
-      allow_commit ? EXIT_CODE_ALLOW_COMMIT : EXIT_CODE_REJECT_COMMIT
     rescue Interrupt # Ctrl-c
       EXIT_CODE_REJECT_COMMIT
     end
 
     private
 
+    def ask_force_commit
+      return unless interactive?
+      stderr.print "\nForce commit? [y/n] "
+      stdin.gets =~ /y/i
+    end
+
+    def interactive?
+      stdin.tty?
+    end
+
     def run_validators
       validators.each do |validator|
         validator.validate(lines)

Diff for: templates/hooks/commit-msg

@@ -1,13 +1,4 @@
 #!/usr/bin/env sh
-#
-# This hook will attempt to setup your environment before running checks.
-
-if which rvm > /dev/null 2>&1
-then cmd="rvm default do ruby"
-elif which rbenv > /dev/null 2>&1
-then cmd="rbenv exec ruby"
-else cmd="ruby"
-fi
 
 export COMMIT_MESSAGE_PATH=$1
 if [ -z "$COMMIT_MESSAGE_PATH" ]; then
@@ -35,7 +26,19 @@ if [ -z "$GIT_BRANCH_NAME" ]; then
   exit 0
 fi
 
-${cmd} -rrubygems -e '
+if which rvm > /dev/null 2>&1
+then cmd="rvm default do ruby"
+elif which rbenv > /dev/null 2>&1
+then cmd="rbenv exec ruby"
+else cmd="ruby"
+fi
+
+# allow user input if running in a terminal
+if [ -t 1 ]; then
+  exec < /dev/tty
+fi
+
+$cmd -rrubygems -e '
   begin
     require "fit_commit"
     true
@@ -46,4 +49,4 @@ fit-commit: Did you set your Ruby version?
 MESSAGE
     false
   end and FitCommit.run
-' < /dev/tty
+'

Diff for: test/unit/runner_test.rb

@@ -65,31 +65,49 @@ def call_runner
   describe "commit msg contains errors" do
     let(:commit_msg) { "foo.\nbar" }
 
-    def assert_error_output
+    def assert_error_output(interactive: true)
       stderr_lines = stderr.read.lines.map(&:chomp)
-      assert_equal 8, stderr_lines.size
+      expected_lines = interactive ? 8 : 6
+      assert_equal expected_lines, stderr_lines.size
       assert_equal commit_msg, stderr_lines[0..1].join("\n")
       assert_empty stderr_lines[2]
       assert_match(/\A1: Error: /, stderr_lines[3])
       assert_match(/\A1: Error: /, stderr_lines[4])
       assert_match(/\A2: Error: /, stderr_lines[5])
-      assert_empty stderr_lines[6]
-      assert_equal "Force commit? [y/n] ", stderr_lines[7]
+      if interactive
+        assert_empty stderr_lines[6]
+        assert_equal "Force commit? [y/n] ", stderr_lines[7]
+      end
+    end
+
+    def fake_tty(text)
+      StringIO.new(text).tap do |stringio|
+        def stringio.tty?
+          true
+        end
+      end
     end
 
     describe "user does not force commit" do
-      let(:stdin) { StringIO.new("n") }
+      let(:stdin) { fake_tty("n") }
       it "prints errors to stderr and rejects commit" do
         assert_equal FitCommit::Runner::EXIT_CODE_REJECT_COMMIT, call_runner
         assert_error_output
       end
     end
     describe "user forces commit" do
-      let(:stdin) { StringIO.new("y") }
+      let(:stdin) { fake_tty("y") }
       it "prints errors to stderr and allows commit" do
         assert_equal FitCommit::Runner::EXIT_CODE_ALLOW_COMMIT, call_runner
         assert_error_output
       end
     end
+    describe "TTY not available" do
+      let(:stdin) { StringIO.new("") }
+      it "prints errors to stderr and rejects commit" do
+        assert_equal FitCommit::Runner::EXIT_CODE_REJECT_COMMIT, call_runner
+        assert_error_output(interactive: false)
+      end
+    end
   end
 end