Test literal equality handling on insert/delete

When `:literal_equality` is supported, ensure that RDF term-equality is
preserved on write operations.

Author: Tom Johnson

lib/rdf/spec/mutable.rb

@@ -11,6 +11,7 @@
     skip "Immutable resource" unless mutable.mutable?
     @statements = RDF::Spec.triples
     @supports_named_graphs = mutable.respond_to?(:supports?) && mutable.supports?(:graph_name)
+    @supports_literal_equality = mutable.respond_to?(:supports?) && mutable.supports?(:literal_equality)
   end
 
   let(:resource) { RDF::URI('http://rubygems.org/gems/rdf') }
@@ -189,7 +190,30 @@
         subject.delete(s3)
         expect(subject.count).to eq count - (@supports_named_graphs ? 3 : 1)
       end
-      
+
+      it 'does not delete literal with different language' do
+        if subject.mutable?
+          en = RDF::Literal('abc', language: 'en')
+          fi = RDF::Literal('abc', language: 'fi')
+
+          subject.insert([RDF::URI('s'), RDF::URI('p'), en])
+          expect { subject.delete([RDF::URI('s'), RDF::URI('p'), fi]) }
+            .not_to change { subject.count }
+        end
+      end
+
+      it 'does not delete literal with different datatype' do
+        if subject.mutable? && @supports_literal_equality
+          float = RDF::Literal::Float.new(1.0)
+          double = RDF::Literal::Double.new(1.0)
+
+          subject.insert([RDF::URI('s'), RDF::URI('p'), float])
+          
+          expect { subject.delete([RDF::URI('s'), RDF::URI('p'), double]) }
+            .not_to change { subject.count }
+        end
+      end
+
       describe '#delete_insert' do
         let(:statement) do
           RDF::Statement.new(resource, 

lib/rdf/spec/writable.rb

@@ -5,6 +5,7 @@
   let(:filename) {RDF::Spec::TRIPLES_FILE}
   let(:statements) {RDF::NTriples::Reader.new(File.open(filename)).to_a}
   let(:supports_graph_name) {writable.respond_to?(:supports?) && writable.supports?(:graph_name)}
+  let(:supports_literal_equality) {writable.respond_to?(:supports?) && writable.supports?(:literal_equality)}
 
   before :each do
     raise 'writable must be defined in with let(:writable)' unless
@@ -88,6 +89,30 @@
       expect(subject.count).to eq 1
     end
 
+    it "should insert statement with literal with unique language" do
+      if subject.writable?
+        statement.object = RDF::Literal('abc', language: 'en')
+        subject.insert(statement)
+
+        statement.object = RDF::Literal('abc', language: 'fi')
+        subject.insert(statement)
+
+        expect(subject.count).to eq 2
+      end
+    end
+
+    it "should insert statement with literal with unique datatype" do
+      if subject.writable? && supports_literal_equality
+        statement.object = RDF::Literal::Float.new(1.0)
+        subject.insert(statement)
+
+        statement.object = RDF::Literal::Double.new(1.0)
+        subject.insert(statement)
+
+        expect(subject.count).to eq 2
+      end
+    end
+
     it "should not insert an incomplete statement" do
       expect {subject.insert(RDF::Statement.from(statement.to_hash.merge(subject: nil)))}.to raise_error(ArgumentError)
       expect {subject.insert(RDF::Statement.from(statement.to_hash.merge(predicate: nil)))}.to raise_error(ArgumentError)