1 files changed, 103 insertions, 0 deletions
diff --git a/spec/tasks/gitlab/db/decomposition/rollback/bump_ci_sequences_rake_spec.rb b/spec/tasks/gitlab/db/decomposition/rollback/bump_ci_sequences_rake_spec.rb
new file mode 100644
index 00000000000..29b80176ef8
--- /dev/null
+++ b/spec/tasks/gitlab/db/decomposition/rollback/bump_ci_sequences_rake_spec.rb
@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+require 'rake_helper'
+
+RSpec.describe 'gitlab:db:decomposition:rollback:bump_ci_sequences', :silence_stdout do
+  before :all do
+    Rake.application.rake_require 'tasks/gitlab/db/decomposition/rollback/bump_ci_sequences'
+
+    # empty task as env is already loaded
+    Rake::Task.define_task :environment
+  end
+
+  let(:expected_error_message) do
+    <<-EOS.strip_heredoc
+      Please specify a positive integer `increase_by` value
+      Example: rake gitlab:db:decomposition:rollback:bump_ci_sequences[100000]
+    EOS
+  end
+
+  let(:main_sequence_name) { 'issues_id_seq' }
+  let(:ci_sequence_name) { 'ci_build_needs_id_seq' }
+
+  # This is just to make sure that all of the sequences start with `is_called=True`
+  # which means that the next call to nextval() is going to increment the sequence.
+  # To give predictable test results.
+  before do
+    ApplicationRecord.connection.select_value("select nextval($1)", nil, [ci_sequence_name])
+  end
+
+  context 'when passing wrong argument' do
+    it 'will print an error message and exit when passing no argument' do
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences')
+      end.to raise_error(SystemExit) { |error| expect(error.status).to eq(1) }
+      .and output(expected_error_message).to_stdout
+    end
+
+    it 'will print an error message and exit when passing a non positive integer value' do
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '-5')
+      end.to raise_error(SystemExit) { |error| expect(error.status).to eq(1) }
+      .and output(expected_error_message).to_stdout
+    end
+  end
+
+  context 'when bumping the ci sequences' do
+    it 'changes ci sequences by the passed argument `increase_by` value on the main database' do
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '15')
+      end.to change {
+        last_value_of_sequence(ApplicationRecord.connection, ci_sequence_name)
+      }.by(16) # the +1 is because the sequence has is_called = true
+    end
+
+    it 'will still increase the value of sequences that have is_called = False' do
+      # see `is_called`: https://www.postgresql.org/docs/12/functions-sequence.html
+      # choosing a new arbitrary value for the sequence
+      new_value = last_value_of_sequence(ApplicationRecord.connection, ci_sequence_name) + 1000
+      ApplicationRecord.connection.select_value("select setval($1, $2, false)", nil, [ci_sequence_name, new_value])
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '15')
+      end.to change {
+        last_value_of_sequence(ApplicationRecord.connection, ci_sequence_name)
+      }.by(15)
+    end
+
+    it 'resets the INCREMENT value of the sequences back to 1 for the following calls to nextval()' do
+      run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '15')
+      value_1 = ApplicationRecord.connection.select_value("select nextval($1)", nil, [ci_sequence_name])
+      value_2 = ApplicationRecord.connection.select_value("select nextval($1)", nil, [ci_sequence_name])
+      expect(value_2 - value_1).to eq(1)
+    end
+
+    it 'does not change the sequences on the gitlab_main tables' do
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '10')
+      end.to change {
+        last_value_of_sequence(ApplicationRecord.connection, main_sequence_name)
+      }.by(0)
+      .and change {
+        last_value_of_sequence(ApplicationRecord.connection, ci_sequence_name)
+      }.by(11) # the +1 is because the sequence has is_called = true
+    end
+  end
+
+  context 'when multiple databases' do
+    before do
+      skip_if_multiple_databases_not_setup
+    end
+
+    it 'does not change ci sequences on the ci database' do
+      expect do
+        run_rake_task('gitlab:db:decomposition:rollback:bump_ci_sequences', '10')
+      end.to change {
+        last_value_of_sequence(Ci::ApplicationRecord.connection, ci_sequence_name)
+      }.by(0)
+    end
+  end
+end
+
+def last_value_of_sequence(connection, sequence_name)
+  connection.select_value("select last_value from #{sequence_name}")
+end