1 files changed, 104 insertions, 0 deletions
diff --git a/spec/tooling/danger/change_column_default_spec.rb b/spec/tooling/danger/change_column_default_spec.rb
new file mode 100644
index 00000000000..8cfcbfa1dc0
--- /dev/null
+++ b/spec/tooling/danger/change_column_default_spec.rb
@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+require 'danger'
+require 'gitlab/dangerfiles/spec_helper'
+
+require_relative '../../../tooling/danger/change_column_default'
+require_relative '../../../tooling/danger/project_helper'
+
+RSpec.describe Tooling::Danger::ChangeColumnDefault, feature_category: :tooling do
+  subject(:change_column_default) { fake_danger.new(helper: fake_helper) }
+
+  let(:fake_danger) { DangerSpecHelper.fake_danger.include(described_class) }
+  let(:fake_project_helper) { instance_double(Tooling::Danger::ProjectHelper) }
+  let(:comment) { described_class::COMMENT.chomp }
+  let(:file_diff) do
+    File.read(File.expand_path("../fixtures/change_column_default_migration.txt", __dir__)).split("\n")
+  end
+
+  include_context "with dangerfile"
+
+  describe '#add_comment_for_change_column_default' do
+    let(:file_lines) { file_diff.map { |line| line.delete_prefix('+').delete_prefix('-') } }
+    let(:matching_lines) { [7, 9, 11] }
+
+    before do
+      allow(change_column_default).to receive(:project_helper).and_return(fake_project_helper)
+      allow(change_column_default.project_helper).to receive(:file_lines).and_return(file_lines)
+      allow(change_column_default.helper).to receive(:all_changed_files).and_return([filename])
+      allow(change_column_default.helper).to receive(:changed_lines).with(filename).and_return(file_diff)
+    end
+
+    context 'when column default is changed in a regular migration' do
+      let(:filename) { 'db/migrate/change_column_default_migration.rb' }
+
+      it 'adds comment at the correct line' do
+        matching_lines.each do |line_number|
+          expect(change_column_default).to receive(:markdown).with("\n#{comment}", file: filename, line: line_number)
+        end
+
+        change_column_default.add_comment_for_change_column_default
+      end
+    end
+
+    context 'when column default is changed in a post-deployment migration' do
+      let(:filename) { 'db/post_migrate/change_column_default_migration.rb' }
+
+      it 'adds comment at the correct line' do
+        matching_lines.each do |line_number|
+          expect(change_column_default).to receive(:markdown).with("\n#{comment}", file: filename, line: line_number)
+        end
+
+        change_column_default.add_comment_for_change_column_default
+      end
+    end
+
+    context 'when a regular migration does not change column default' do
+      let(:filename) { 'db/migrate/my_migration.rb' }
+      let(:file_diff) do
+        [
+          "+    undo_cleanup_concurrent_column_rename(:my_table, :old_column, :new_column)",
+          "-    cleanup_concurrent_column_rename(:my_table, :new_column, :old_column)"
+        ]
+      end
+
+      let(:file_lines) do
+        [
+          '  def up',
+          '    undo_cleanup_concurrent_column_rename(:my_table, :old_column, :new_column)',
+          '  end'
+        ]
+      end
+
+      it 'does not add comment' do
+        expect(change_column_default).not_to receive(:markdown)
+
+        change_column_default.add_comment_for_change_column_default
+      end
+    end
+
+    context 'when a post-deployment migration does not change column default' do
+      let(:filename) { 'db/post_migrate/my_migration.rb' }
+      let(:file_diff) do
+        [
+          "+    restore_conversion_of_integer_to_bigint(TABLE, COLUMNS)",
+          "-    cleanup_conversion_of_integer_to_bigint(TABLE, COLUMNS)"
+        ]
+      end
+
+      let(:file_lines) do
+        [
+          '  def up',
+          '    cleanup_conversion_of_integer_to_bigint(TABLE, COLUMNS)',
+          '  end'
+        ]
+      end
+
+      it 'does not add comment' do
+        expect(change_column_default).not_to receive(:markdown)
+
+        change_column_default.add_comment_for_change_column_default
+      end
+    end
+  end
+end