1 files changed, 78 insertions, 0 deletions
diff --git a/spec/lib/gitlab/database/schema_migrations/context_spec.rb b/spec/lib/gitlab/database/schema_migrations/context_spec.rb
new file mode 100644
index 00000000000..f3bed9b40d6
--- /dev/null
+++ b/spec/lib/gitlab/database/schema_migrations/context_spec.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Database::SchemaMigrations::Context do
+  let(:connection) { ActiveRecord::Base.connection }
+
+  let(:context) { described_class.new(connection) }
+
+  describe '#schema_directory' do
+    it 'returns db/schema_migrations' do
+      expect(context.schema_directory).to eq(File.join(Rails.root, 'db/schema_migrations'))
+    end
+
+    context 'multiple databases' do
+      let(:connection) { Ci::BaseModel.connection }
+
+      it 'returns a directory path that is database specific' do
+        skip_if_multiple_databases_not_setup
+
+        expect(context.schema_directory).to eq(File.join(Rails.root, 'db/ci_schema_migrations'))
+      end
+    end
+  end
+
+  describe '#versions_to_create' do
+    before do
+      allow(connection).to receive_message_chain(:schema_migration, :all_versions).and_return(migrated_versions)
+
+      migrations_struct = Struct.new(:version)
+      migrations = file_versions.map { |version| migrations_struct.new(version) }
+      allow(connection).to receive_message_chain(:migration_context, :migrations).and_return(migrations)
+    end
+
+    let(:version1) { '20200123' }
+    let(:version2) { '20200410' }
+    let(:version3) { '20200602' }
+    let(:version4) { '20200809' }
+
+    let(:migrated_versions) { file_versions }
+    let(:file_versions) { [version1, version2, version3, version4] }
+
+    context 'migrated versions is the same as migration file versions' do
+      it 'returns migrated versions' do
+        expect(context.versions_to_create).to eq(migrated_versions)
+      end
+    end
+
+    context 'migrated versions is subset of migration file versions' do
+      let(:migrated_versions) { [version1, version2] }
+
+      it 'returns migrated versions' do
+        expect(context.versions_to_create).to eq(migrated_versions)
+      end
+    end
+
+    context 'migrated versions is superset of migration file versions' do
+      let(:migrated_versions) { file_versions + ['20210809'] }
+
+      it 'returns file versions' do
+        expect(context.versions_to_create).to eq(file_versions)
+      end
+    end
+
+    context 'migrated versions has slightly different versions to migration file versions' do
+      let(:migrated_versions) { [version1, version2, version3, version4, '20210101'] }
+      let(:file_versions) { [version1, version2, version3, version4, '20210102'] }
+
+      it 'returns the common set' do
+        expect(context.versions_to_create).to eq([version1, version2, version3, version4])
+      end
+    end
+  end
+
+  def skip_if_multiple_databases_not_setup
+    skip 'Skipping because multiple databases not set up' unless Gitlab::Database.has_config?(:ci)
+  end
+end