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diff --git a/spec/migrations/README.md b/spec/migrations/README.md index 4d86d30080a..5065df3fbef 100644 --- a/spec/migrations/README.md +++ b/spec/migrations/README.md @@ -1,137 +1 @@ -# Testing migrations - -In order to reliably test a migration, we need to test it against a database -schema that this migration has been written for. In order to achieve that we -have some _migration helpers_ and RSpec test tag, called `:migration`. - -If you want to write a test for a migration consider adding `:migration` tag to -the test signature, like `describe SomeMigrationClass, :migration`. - -## How does it work? - -Adding a `:migration` tag to a test signature injects a few before / after -hooks to the test. - -The most important change is that adding a `:migration` tag adds a `before` -hook that will revert all migrations to the point that a migration under test -is not yet migrated. - -In other words, our custom RSpec hooks will find a previous migration, and -migrate the database **down** to the previous migration version. - -With this approach you can test a migration against a database schema that this -migration has been written for. - -The `after` hook will migrate the database **up** and reinstitutes the latest -schema version, so that the process does not affect subsequent specs and -ensures proper isolation. - -## Available helpers - -Use `table` helper to create a temporary `ActiveRecord::Base` derived model -for a table. - -See `spec/support/helpers/migrations_helpers.rb` for all the available helpers. - -## Testing a class that is an ActiveRecord::Migration - -In order to test a class that is an `ActiveRecord::Migration`, you will need to -manually `require` the migration file because it is not autoloaded with Rails. - -Use `migrate!` helper to run the migration that is under test. It will not only -run migration, but will also bump the schema version in the `schema_migrations` -table. It is necessary because in the `after` hook we trigger the rest of -the migrations, and we need to know where to start. - -### Example - -This spec tests the [`db/post_migrate/20170526185842_migrate_pipeline_stages.rb`](https://gitlab.com/gitlab-org/gitlab-foss/blob/v11.6.5/db/post_migrate/20170526185842_migrate_pipeline_stages.rb) migration. You can find the complete spec on [`spec/migrations/migrate_pipeline_stages_spec.rb`](https://gitlab.com/gitlab-org/gitlab-foss/blob/v11.6.5/spec/migrations/migrate_pipeline_stages_spec.rb). - -```ruby -require 'spec_helper' -require Rails.root.join('db', 'post_migrate', '20170526185842_migrate_pipeline_stages.rb') - -describe MigratePipelineStages, :migration do - - # Create test data - pipeline and CI/CD jobs. - - let(:jobs) { table(:ci_builds) } - let(:stages) { table(:ci_stages) } - let(:pipelines) { table(:ci_pipelines) } - let(:projects) { table(:projects) } - - before do - projects.create!(id: 123, name: 'gitlab1', path: 'gitlab1') - pipelines.create!(id: 1, project_id: 123, ref: 'master', sha: 'adf43c3a') - jobs.create!(id: 1, commit_id: 1, project_id: 123, stage_idx: 2, stage: 'build') - jobs.create!(id: 2, commit_id: 1, project_id: 123, stage_idx: 1, stage: 'test') - end - - # Test the migration. - - it 'correctly migrates pipeline stages' do - expect(stages.count).to be_zero - - migrate! - - expect(stages.count).to eq 2 - expect(stages.all.pluck(:name)).to match_array %w[test build] - end -end -``` - -## Testing a class that is not an ActiveRecord::Migration - -To test a class that is not an `ActiveRecord::Migration` (a background migration), -you will need to manually provide a required schema version. Please add a -schema tag to a context that you want to switch the database schema within. - -Example: `describe SomeClass, :migration, schema: 20170608152748`. - -### Example - -This spec tests the [`lib/gitlab/background_migration/archive_legacy_traces.rb`](https://gitlab.com/gitlab-org/gitlab-foss/blob/v11.6.5/lib/gitlab/background_migration/archive_legacy_traces.rb) -background migration. You can find the complete spec on -[`spec/lib/gitlab/background_migration/archive_legacy_traces_spec.rb`](https://gitlab.com/gitlab-org/gitlab-foss/blob/v11.6.5/spec/lib/gitlab/background_migration/archive_legacy_traces_spec.rb) - -```ruby -require 'spec_helper' - -describe Gitlab::BackgroundMigration::ArchiveLegacyTraces, :migration, schema: 20180529152628 do - include TraceHelpers - - let(:namespaces) { table(:namespaces) } - let(:projects) { table(:projects) } - let(:builds) { table(:ci_builds) } - let(:job_artifacts) { table(:ci_job_artifacts) } - - before do - namespaces.create!(id: 123, name: 'gitlab1', path: 'gitlab1') - projects.create!(id: 123, name: 'gitlab1', path: 'gitlab1', namespace_id: 123) - @build = builds.create!(id: 1, project_id: 123, status: 'success', type: 'Ci::Build') - end - - context 'when trace file exsits at the right place' do - before do - create_legacy_trace(@build, 'trace in file') - end - - it 'correctly archive legacy traces' do - expect(job_artifacts.count).to eq(0) - expect(File.exist?(legacy_trace_path(@build))).to be_truthy - - described_class.new.perform(1, 1) - - expect(job_artifacts.count).to eq(1) - expect(File.exist?(legacy_trace_path(@build))).to be_falsy - expect(File.read(archived_trace_path(job_artifacts.first))).to eq('trace in file') - end - end -end -``` - -## Best practices - -1. Note that this type of tests do not run within the transaction, we use -a deletion database cleanup strategy. Do not depend on transaction being -present. +This document was moved to [another location](https://docs.gitlab.com/ee/development/testing_guide/testing_migrations_guide.html). |