1 files changed, 54 insertions, 0 deletions
diff --git a/spec/tooling/danger/merge_request_linter_spec.rb b/spec/tooling/danger/merge_request_linter_spec.rb
new file mode 100644
index 00000000000..3273b6b3d07
--- /dev/null
+++ b/spec/tooling/danger/merge_request_linter_spec.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require 'rspec-parameterized'
+require_relative 'danger_spec_helper'
+
+require_relative '../../../tooling/danger/merge_request_linter'
+
+RSpec.describe Tooling::Danger::MergeRequestLinter do
+  using RSpec::Parameterized::TableSyntax
+
+  let(:mr_class) do
+    Struct.new(:message, :sha, :diff_parent)
+  end
+
+  let(:mr_title) { 'A B ' + 'C' }
+  let(:merge_request) { mr_class.new(mr_title, anything, anything) }
+
+  describe '#lint_subject' do
+    subject(:mr_linter) { described_class.new(merge_request) }
+
+    shared_examples 'a valid mr title' do
+      it 'does not have any problem' do
+        mr_linter.lint
+
+        expect(mr_linter.problems).to be_empty
+      end
+    end
+
+    context 'when subject valid' do
+      it_behaves_like 'a valid mr title'
+    end
+
+    context 'when it is too long' do
+      let(:mr_title) { 'A B ' + 'C' * described_class::MAX_LINE_LENGTH }
+
+      it 'adds a problem' do
+        expect(mr_linter).to receive(:add_problem).with(:subject_too_long, described_class.subject_description)
+
+        mr_linter.lint
+      end
+    end
+
+    describe 'using magic mr run options' do
+      where(run_option: described_class.mr_run_options_regex.split('|') +
+        described_class.mr_run_options_regex.split('|').map! { |x| "[#{x}]" })
+
+      with_them do
+        let(:mr_title) { run_option + ' A B ' + 'C' * (described_class::MAX_LINE_LENGTH - 5) }
+
+        it_behaves_like 'a valid mr title'
+      end
+    end
+  end
+end