1 files changed, 159 insertions, 0 deletions
diff --git a/spec/tooling/lib/tooling/find_tests_spec.rb b/spec/tooling/lib/tooling/find_tests_spec.rb
new file mode 100644
index 00000000000..905f81c4bbd
--- /dev/null
+++ b/spec/tooling/lib/tooling/find_tests_spec.rb
@@ -0,0 +1,159 @@
+# frozen_string_literal: true
+
+require 'tempfile'
+require_relative '../../../../tooling/lib/tooling/find_tests'
+require_relative '../../../support/helpers/stub_env'
+
+RSpec.describe Tooling::FindTests, feature_category: :tooling do
+  include StubENV
+
+  attr_accessor :changed_files_file, :predictive_tests_file
+
+  let(:instance)                     { described_class.new(changed_files_pathname, predictive_tests_pathname) }
+  let(:mock_test_file_finder)        { instance_double(TestFileFinder::FileFinder) }
+  let(:new_matching_tests)           { ["new_matching_spec.rb"] }
+  let(:changed_files_pathname)       { changed_files_file.path }
+  let(:predictive_tests_pathname)    { predictive_tests_file.path }
+  let(:changed_files_content)        { "changed_file1 changed_file2" }
+  let(:predictive_tests_content)     { "previously_matching_spec.rb" }
+
+  around do |example|
+    self.changed_files_file    = Tempfile.new('changed_files_file')
+    self.predictive_tests_file = Tempfile.new('predictive_tests_file')
+
+    # See https://ruby-doc.org/stdlib-1.9.3/libdoc/tempfile/rdoc/
+    #     Tempfile.html#class-Tempfile-label-Explicit+close
+    begin
+      example.run
+    ensure
+      changed_files_file.close
+      predictive_tests_file.close
+      changed_files_file.unlink
+      predictive_tests_file.unlink
+    end
+  end
+
+  before do
+    allow(mock_test_file_finder).to receive(:use)
+    allow(mock_test_file_finder).to receive(:test_files).and_return(new_matching_tests)
+    allow(TestFileFinder::FileFinder).to receive(:new).and_return(mock_test_file_finder)
+
+    stub_env(
+      'RSPEC_TESTS_MAPPING_ENABLED' => nil,
+      'RSPEC_TESTS_MAPPING_PATH' => '/tmp/does-not-exist.out'
+    )
+
+    # We write into the temp files initially, to later check how the code modified those files
+    File.write(changed_files_pathname, changed_files_content)
+    File.write(predictive_tests_pathname, predictive_tests_content)
+  end
+
+  describe '#execute' do
+    subject { instance.execute }
+
+    context 'when the predictive_tests_pathname file does not exist' do
+      let(:instance) { described_class.new(non_existing_output_pathname, predictive_tests_pathname) }
+      let(:non_existing_output_pathname) { 'tmp/another_file.out' }
+
+      around do |example|
+        example.run
+      ensure
+        FileUtils.rm_rf(non_existing_output_pathname)
+      end
+
+      it 'creates the file' do
+        expect { subject }.to change { File.exist?(non_existing_output_pathname) }.from(false).to(true)
+      end
+    end
+
+    context 'when the predictive_tests_pathname file already exists' do
+      it 'does not create an empty file' do
+        expect(File).not_to receive(:write).with(predictive_tests_pathname, '')
+
+        subject
+      end
+    end
+
+    it 'does not modify the content of the input file' do
+      expect { subject }.not_to change { File.read(changed_files_pathname) }
+    end
+
+    it 'does not overwrite the output file' do
+      expect { subject }.to change { File.read(predictive_tests_pathname) }
+                        .from(predictive_tests_content)
+                        .to("#{predictive_tests_content} #{new_matching_tests.uniq.join(' ')}")
+    end
+
+    it 'loads the tests.yml file with a pattern matching mapping' do
+      expect(TestFileFinder::MappingStrategies::PatternMatching).to receive(:load).with('tests.yml')
+
+      subject
+    end
+
+    context 'when RSPEC_TESTS_MAPPING_ENABLED env variable is set' do
+      before do
+        stub_env(
+          'RSPEC_TESTS_MAPPING_ENABLED' => 'true',
+          'RSPEC_TESTS_MAPPING_PATH' => 'crystalball-test/mapping.json'
+        )
+      end
+
+      it 'loads the direct matching pattern file' do
+        expect(TestFileFinder::MappingStrategies::DirectMatching)
+          .to receive(:load_json)
+          .with('crystalball-test/mapping.json')
+
+        subject
+      end
+    end
+
+    context 'when RSPEC_TESTS_MAPPING_ENABLED env variable is not set' do
+      let(:rspec_tests_mapping_enabled) { '' }
+
+      before do
+        stub_env(
+          'RSPEC_TESTS_MAPPING_ENABLED' => rspec_tests_mapping_enabled,
+          'RSPEC_TESTS_MAPPING_PATH' => rspec_tests_mapping_path
+        )
+      end
+
+      context 'when RSPEC_TESTS_MAPPING_PATH is set' do
+        let(:rspec_tests_mapping_path) { 'crystalball-test/mapping.json' }
+
+        it 'does not load the direct matching pattern file' do
+          expect(TestFileFinder::MappingStrategies::DirectMatching).not_to receive(:load_json)
+
+          subject
+        end
+      end
+
+      context 'when RSPEC_TESTS_MAPPING_PATH is not set' do
+        let(:rspec_tests_mapping_path) { nil }
+
+        it 'does not load the direct matching pattern file' do
+          expect(TestFileFinder::MappingStrategies::DirectMatching).not_to receive(:load_json)
+
+          subject
+        end
+      end
+    end
+
+    context 'when the same spec is matching multiple times' do
+      let(:new_matching_tests) do
+        [
+          "new_matching_spec.rb",
+          "duplicate_spec.rb",
+          "duplicate_spec.rb"
+        ]
+      end
+
+      it 'writes uniquely matching specs to the output' do
+        subject
+
+        expect(File.read(predictive_tests_pathname).split(' ')).to match_array(
+          predictive_tests_content.split(' ') + new_matching_tests.uniq
+        )
+      end
+    end
+  end
+end