+
+ describe '#neighbours' do
+ it 'finds neighbours of a self loop' do
+ v << v
+ v.should have(1).neighbours
+ v.neighbours.should include v
+ end
+
+ it 'finds neighbours on an edge' do
+ v1 = Vertex.new
+ v << v1
+ v.should have(1).neighbours
+ v.neighbours.should include v1
+ v1.should have(1).neighbours
+ v1.neighbours.should include v
+ end
+
+ it 'finds neighbours with multiple edges' do
+ v1 = Vertex.new
+ v1.id = :v1
+ v << v1
+ v1 << v
+ v.should have(2).neighbours
+ v.neighbours.should include v1
+ v.neighbours.should_not include v
+ v1.should have(2).neighbours
+ v1.neighbours.should include v
+ v1.neighbours.should_not include v1
+ end
+
+ it 'finds neighbours with multiple self loops' do
+ v << v << v << v
+ v.should have(3).neighbours
+ v.neighbours.should include v
+ v.neighbours.uniq.length.should == 1
+ end
+
+ it 'finds neighbours with all sorts of edges' do
+ v1 = Vertex.new ; v1.id = :v1
+ v2 = Vertex.new ; v2.id = :v2
+ v3 = Vertex.new ; v3.id = :v3
+ v1 << v
+ v << v2
+ v2 << v3
+ v2 << v2
+
+ v.should have(2).neighbours
+ v.neighbours.should include v1
+ v.neighbours.should include v2
+
+ v1.should have(1).neighbours
+ v1.neighbours.should include v
+
+ v2.should have(3).neighbours
+ v2.neighbours.should include v
+ v2.neighbours.should include v2
+ v2.neighbours.should include v3
+
+ v3.should have(1).neighbours
+ v3.neighbours.should include v2
+ end
+
+ it 'finds neighbours in graphs with several vertices' do
+ v1 = Vertex.new ; v1.id = :v1
+ v2 = Vertex.new ; v2.id = :v2
+ v3 = Vertex.new ; v3.id = :v3
+ v4 = Vertex.new ; v4.id = :v4
+ v << v1
+ v1 << v2
+ v2 << v3
+ v << v3
+ v4 << v3
+ v.should have(2).neighbours
+ v.neighbours.should include v1
+ v.neighbours.should include v3
+ v.neighbours.should_not include v
+ v1.should have(2).neighbours
+ v1.neighbours.should include v
+ v1.neighbours.should include v2
+ v1.neighbours.should_not include v1
+ v2.should have(2).neighbours
+ v2.neighbours.should include v1
+ v2.neighbours.should include v3
+ v2.neighbours.should_not include v2
+ v3.should have(3).neighbours
+ v3.neighbours.should include v
+ v3.neighbours.should include v2
+ v3.neighbours.should include v4
+ v3.neighbours.should_not include v3
+ v4.should have(1).neighbours
+ v4.neighbours.should include v3
+ v4.neighbours.should_not include v4
+ end
+
+ it 'finds neighbours with multiple edges between vertices' do
+ v1 = Vertex.new ; v1.id = :v1
+ v2 = Vertex.new ; v2.id = :v2
+ v3 = Vertex.new ; v3.id = :v3
+ v1 << v1 << v
+ v << v2
+ v << v
+ v3 << v2
+ v2 << v3
+ v2 << v2
+
+ v.should have(3).neighbours
+ v.neighbours.should include v1
+ v.neighbours.should include v2
+ v.neighbours.should include v
+
+ v1.should have(2).neighbours
+ v1.neighbours.should include v
+ v1.neighbours.should include v1
+
+ v2.should have(4).neighbours
+ v2.neighbours.should include v
+ v2.neighbours.should include v2
+ v2.neighbours.should include v3
+ v2.neighbours.uniq.length.should == 3
+
+ v3.should have(2).neighbours
+ v3.neighbours.should include v2
+ v3.neighbours.uniq.length.should == 1
+ end
+ end # #neighbours
+
+ describe '#to_dot' do
+ it 'describes a vertex in dot notation' do
+ v = Vertex.new
+ v.to_dot.should == "#{v.object_id.to_s};"
+ end
+
+ it 'describes a vertex in dot notation, using given attributes' do
+ v = Vertex.new
+ v.name = 'vertex'
+ v.shape = 'house'
+ vdot = v.to_dot :label => :name, :shape => :shape
+ vdot.should == "#{v.object_id.to_s} {label = \"#{v.name}\", shape = \"#{v.shape}\"};"
+ end
+
+ it 'describes a vertex using a block' do
+ v = Vertex.new
+ v.field1 = 'f1'
+ vdot = v.to_dot {|v| v.field1 + ';'}
+ vdot.should == "#{v.field1};"
+ end
+ end # #to_dot