null_test.go

package gogl

import (
	. "github.com/sdboyer/gocheck"
	"math"
)

type NullGraphSuite bool

var _ = Suite(NullGraphSuite(false))

func (s NullGraphSuite) TestEnumerators(c *C) {
	NullGraph.Vertices(func(v Vertex) (terminate bool) {
		c.Error("The NullGraph should not have any vertices.")
		return
	})

	NullGraph.Edges(func(e Edge) (terminate bool) {
		c.Error("The NullGraph should not have any edges.")
		return
	})

	NullGraph.IncidentTo("foo", func(e Edge) (terminate bool) {
		c.Error("The NullGraph should be empty of edges and vertices.")
		return
	})

	NullGraph.AdjacentTo("foo", func(v Vertex) (terminate bool) {
		c.Error("The NullGraph should be empty of edges and vertices.")
		return
	})

	NullGraph.ArcsFrom("foo", func(e Arc) (terminate bool) {
		c.Error("The NullGraph should be empty of edges and vertices.")
		return
	})

	NullGraph.ArcsTo("foo", func(e Arc) (terminate bool) {
		c.Error("The NullGraph should be empty of edges and vertices.")
		return
	})
}

func (s NullGraphSuite) TestMembership(c *C) {
	c.Assert(NullGraph.HasVertex("foo"), Equals, false)                                    // must always be false
	c.Assert(NullGraph.HasEdge(NewEdge("qux", "quark")), Equals, false)                    // must always be false
	c.Assert(NullGraph.HasWeightedEdge(NewWeightedEdge("qux", "quark", 0)), Equals, false) // must always be false
	c.Assert(NullGraph.HasLabeledEdge(NewLabeledEdge("qux", "quark", "")), Equals, false)  // must always be false
	c.Assert(NullGraph.HasDataEdge(NewDataEdge("qux", "quark", func() {})), Equals, false) // must always be false
}

func (s NullGraphSuite) TestDegree(c *C) {
	deg, exists := NullGraph.DegreeOf("foo")
	c.Assert(exists, Equals, false) // vertex is not present in graph
	c.Assert(deg, Equals, 0)        // always will have degree 0

	deg, exists = NullGraph.InDegreeOf("foo")
	c.Assert(exists, Equals, false) // vertex is not present in graph
	c.Assert(deg, Equals, 0)        // always will have indegree 0

	deg, exists = NullGraph.OutDegreeOf("foo")
	c.Assert(exists, Equals, false) // vertex is not present in graph
	c.Assert(deg, Equals, 0)        // always will have outdegree 0
}

func (s NullGraphSuite) TestSizingOps(c *C) {
	c.Assert(math.IsNaN(NullGraph.Density()), Equals, true)
}

func (s NullGraphSuite) TestTranspose(c *C) {
	c.Assert(NullGraph.Transpose(), Equals, NullGraph)
}