Parser: avoid Ruby exit

- made the method take three arguments
- specs all note these three

lib/github_changelog_generator/parser.rb

@@ -217,7 +217,7 @@ module GitHubChangelogGenerator
     #
     # @param [String] output of git remote command
     # @return [Array] user and project
-    def self.user_project_from_option(arg0, arg1, github_site = nil)
+    def self.user_project_from_option(arg0, arg1, github_site)
       user = nil
       project = nil
       github_site ||= "github.com"
@@ -230,10 +230,10 @@ module GitHubChangelogGenerator
           param = match[2].nil?
         rescue
           puts "Can't detect user and name from first parameter: '#{arg0}' -> exit'"
-          exit
+          return
         end
         if param
-          exit
+          return
         else
           user = match[1]
           project = match[2]
@@ -276,9 +276,4 @@ module GitHubChangelogGenerator
       [user, project]
     end
   end
-
-  if __FILE__ == $PROGRAM_NAME
-    remote = "invalid reference to project"
-    p user_project_from_option(ARGV[0], ARGV[1], remote)
-  end
 end

spec/unit/parser_spec.rb

@@ -28,16 +28,16 @@ describe GitHubChangelogGenerator::Parser do
   end
   describe ".user_project_from_option" do
     context "when option is invalid" do
-      it("should exit") { expect { GitHubChangelogGenerator::Parser.user_project_from_option("blah", nil) }.to raise_error(SystemExit) }
+      it("should return nil") { expect(GitHubChangelogGenerator::Parser.user_project_from_option("blah", nil, nil)).to be_nil }
     end
 
     context "when option is valid" do
-      subject { GitHubChangelogGenerator::Parser.user_project_from_option("skywinder/ActionSheetPicker-3.0", nil) }
+      subject { GitHubChangelogGenerator::Parser.user_project_from_option("skywinder/ActionSheetPicker-3.0", nil, nil) }
       it { is_expected.to be_a(Array) }
       it { is_expected.to match_array(["skywinder", "ActionSheetPicker-3.0"]) }
     end
     context "when option nil" do
-      subject { GitHubChangelogGenerator::Parser.user_project_from_option(nil, nil) }
+      subject { GitHubChangelogGenerator::Parser.user_project_from_option(nil, nil, nil) }
       it { is_expected.to be_a(Array) }
       it { is_expected.to match_array([nil, nil]) }
     end