Extract Transactable behavior to module

Author: Tom Johnson

lib/rdf/spec/repository.rb

@@ -23,6 +23,12 @@
     require 'rdf/spec/dataset'
     it_behaves_like 'an RDF::Dataset'
   end
+
+  context 'as transactable' do
+    require 'rdf/spec/transactable'
+    let(:transactable) { repository }
+    it_behaves_like 'an RDF::Transactable'
+  end
 
   context "when updating" do
     require 'rdf/spec/mutable'

lib/rdf/spec/transactable.rb

@@ -0,0 +1,43 @@
+require 'rdf/spec'
+
+RSpec.shared_examples 'an RDF::Transactable' do
+  include RDF::Spec::Matchers
+
+  let(:statements) { RDF::Spec.quads }
+
+  before do
+    raise '`transactable` must be set with `let(:transactable)`' unless
+      defined? transactable
+  end
+
+  subject { transactable }
+
+  describe "#transaction" do
+    it 'gives an immutable transaction' do
+      expect { subject.transaction { insert([]) } }.to raise_error TypeError
+    end
+
+    it 'commits a successful transaction' do
+      statement = RDF::Statement(:s, RDF.type, :o)
+      expect(subject).to receive(:commit_transaction).and_call_original
+      
+      expect do
+        subject.transaction(mutable: true) { insert(statement) }
+      end.to change { subject.statements }.to include(statement)
+    end
+
+    it 'rolls back a failed transaction' do
+      original_contents = subject.statements
+      expect(subject).to receive(:rollback_transaction).and_call_original
+
+      expect do
+        subject.transaction(mutable: true) do
+          delete(*@statements)
+          raise 'my error'
+        end
+      end.to raise_error RuntimeError
+
+      expect(subject.statements).to contain_exactly(*original_contents)
+    end
+  end
+end