1 files changed, 42 insertions, 0 deletions
diff --git a/spec/tooling/lib/tooling/crystalball/coverage_lines_execution_detector_spec.rb b/spec/tooling/lib/tooling/crystalball/coverage_lines_execution_detector_spec.rb
new file mode 100644
index 00000000000..6b7373cb3c7
--- /dev/null
+++ b/spec/tooling/lib/tooling/crystalball/coverage_lines_execution_detector_spec.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require_relative '../../../../../tooling/lib/tooling/crystalball/coverage_lines_execution_detector'
+
+RSpec.describe Tooling::Crystalball::CoverageLinesExecutionDetector do
+  subject(:detector) { described_class.new(root, exclude_prefixes: %w[vendor/ruby]) }
+
+  let(:root) { '/tmp' }
+  let(:before_map) { { path => { lines: [0, 2, nil] } } }
+  let(:after_map) { { path => { lines: [0, 3, nil] } } }
+  let(:path) { '/tmp/file.rb' }
+
+  describe '#detect' do
+    subject { detector.detect(before_map, after_map) }
+
+    it { is_expected.to eq(%w[file.rb]) }
+
+    context 'with no changes' do
+      let(:after_map) { { path => { lines: [0, 2, nil] } } }
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'with previously uncovered file' do
+      let(:before_map) { {} }
+
+      it { is_expected.to eq(%w[file.rb]) }
+    end
+
+    context 'with path outside of root' do
+      let(:path) { '/abc/file.rb' }
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'with path in excluded prefix' do
+      let(:path) { '/tmp/vendor/ruby/dependency.rb' }
+
+      it { is_expected.to eq([]) }
+    end
+  end
+end