undirected_test.go

package graph

import (
	"errors"
	"testing"
)

func TestUndirected_Traits(t *testing.T) {
	tests := map[string]struct {
		traits   *Traits
		expected *Traits
	}{
		"default traits": {
			traits:   &Traits{},
			expected: &Traits{},
		},
		"directed": {
			traits:   &Traits{IsDirected: true},
			expected: &Traits{IsDirected: true},
		},
	}

	for name, test := range tests {
		g := newUndirected(IntHash, test.traits, newMemoryStore[int, int]())
		traits := g.Traits()

		if !traitsAreEqual(traits, test.expected) {
			t.Errorf("%s: traits expectancy doesn't match: expected %v, got %v", name, test.expected, traits)
		}
	}
}

func TestUndirected_AddVertex(t *testing.T) {
	tests := map[string]struct {
		vertices           []int
		properties         *VertexProperties
		expectedVertices   []int
		expectedProperties *VertexProperties
		// Even though some AddVertex calls might work, at least one of them
		// could fail, e.g. if the last call would add an existing vertex.
		finallyExpectedError error
	}{
		"graph with 3 vertices": {
			vertices: []int{1, 2, 3},
			properties: &VertexProperties{
				Attributes: map[string]string{"color": "red"},
				Weight:     10,
			},
			expectedVertices: []int{1, 2, 3},
			expectedProperties: &VertexProperties{
				Attributes: map[string]string{"color": "red"},
				Weight:     10,
			},
		},
		"graph with duplicated vertex": {
			vertices:             []int{1, 2, 2},
			expectedVertices:     []int{1, 2},
			finallyExpectedError: ErrVertexAlreadyExists,
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		var err error

		for _, vertex := range test.vertices {
			if test.properties == nil {
				err = graph.AddVertex(vertex)
				continue
			}
			// If there are vertex attributes, iterate over them and call the
			// VertexAttribute functional option for each entry. A vertex should
			// only have one attribute so that AddVertex is invoked once.
			for key, value := range test.properties.Attributes {
				err = graph.AddVertex(vertex, VertexWeight(test.properties.Weight), VertexAttribute(key, value))
			}
		}

		if !errors.Is(err, test.finallyExpectedError) {
			t.Errorf("%s: error expectancy doesn't match: expected %v, got %v", name, test.finallyExpectedError, err)
		}

		graphStore := graph.store.(*memoryStore[int, int])

		for _, vertex := range test.vertices {
			if len(graphStore.vertices) != len(test.expectedVertices) {
				t.Errorf("%s: vertex count doesn't match: expected %v, got %v", name, len(test.expectedVertices), len(graphStore.vertices))
			}

			hash := graph.hash(vertex)
			vertices := graph.store.(*memoryStore[int, int]).vertices
			if _, ok := vertices[hash]; !ok {
				t.Errorf("%s: vertex %v not found in graph: %v", name, vertex, vertices)
			}

			if test.properties == nil {
				continue
			}

			if graphStore.vertexProperties[hash].Weight != test.expectedProperties.Weight {
				t.Errorf("%s: edge weights don't match: expected weight %v, got %v", name, test.expectedProperties.Weight, graphStore.vertexProperties[hash].Weight)
			}

			if len(graphStore.vertexProperties[hash].Attributes) != len(test.expectedProperties.Attributes) {
				t.Fatalf("%s: attributes lengths don't match: expcted %v, got %v", name, len(test.expectedProperties.Attributes), len(graphStore.vertexProperties[hash].Attributes))
			}

			for expectedKey, expectedValue := range test.expectedProperties.Attributes {
				value, ok := graphStore.vertexProperties[hash].Attributes[expectedKey]
				if !ok {
					t.Errorf("%s: attribute keys don't match: expected key %v not found", name, expectedKey)
				}
				if value != expectedValue {
					t.Errorf("%s: attribute values don't match: expected value %v for key %v, got %v", name, expectedValue, expectedKey, value)
				}
			}
		}
	}
}

func TestUndirected_AddVerticesFrom(t *testing.T) {
	tests := map[string]struct {
		vertices           []int
		properties         map[int]VertexProperties
		existingVertices   []int
		expectedVertices   []int
		expectedProperties map[int]VertexProperties
		expectedError      error
	}{
		"graph with 3 vertices": {
			vertices: []int{1, 2, 3},
			properties: map[int]VertexProperties{
				1: {
					Attributes: map[string]string{"color": "red"},
					Weight:     10,
				},
				2: {
					Attributes: map[string]string{"color": "green"},
					Weight:     20,
				},
				3: {
					Attributes: map[string]string{"color": "blue"},
					Weight:     30,
				},
			},
			existingVertices: []int{},
			expectedVertices: []int{1, 2, 3},
			expectedProperties: map[int]VertexProperties{
				1: {
					Attributes: map[string]string{"color": "red"},
					Weight:     10,
				},
				2: {
					Attributes: map[string]string{"color": "green"},
					Weight:     20,
				},
				3: {
					Attributes: map[string]string{"color": "blue"},
					Weight:     30,
				},
			},
		},
		"graph with duplicated vertex": {
			vertices:           []int{1, 2, 3},
			properties:         map[int]VertexProperties{},
			existingVertices:   []int{2},
			expectedVertices:   []int{1},
			expectedProperties: map[int]VertexProperties{},
			expectedError:      ErrVertexAlreadyExists,
		},
	}

	for name, test := range tests {
		t.Run(name, func(t *testing.T) {
			source := New(IntHash)

			for _, vertex := range test.vertices {
				_ = source.AddVertex(vertex, copyVertexProperties(test.properties[vertex]))
			}

			g := New(IntHash)

			for _, vertex := range test.existingVertices {
				_ = g.AddVertex(vertex)
			}

			err := g.AddVerticesFrom(source)

			if !errors.Is(err, test.expectedError) {
				t.Errorf("expected error %v, got %v", test.expectedError, err)
			}

			if err != nil {
				return
			}

			for _, vertex := range test.expectedVertices {
				_, actualProperties, err := g.VertexWithProperties(vertex)
				if err != nil {
					t.Errorf("failed to get vertex %v with properties: %v", vertex, err.Error())
					return
				}

				if expectedProperties, ok := test.expectedProperties[vertex]; ok {
					if !vertexPropertiesAreEqual(expectedProperties, actualProperties) {
						t.Errorf("expected properties %v for %v, got %v", expectedProperties, vertex, actualProperties)
					}
				}
			}
		})
	}
}

func TestUndirected_Vertex(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		vertex        int
		expectedError error
	}{
		"existing vertex": {
			vertices: []int{1, 2, 3},
			vertex:   2,
		},
		"non-existent vertex": {
			vertices:      []int{1, 2, 3},
			vertex:        4,
			expectedError: ErrVertexNotFound,
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		vertex, err := graph.Vertex(test.vertex)

		if !errors.Is(err, test.expectedError) {
			t.Errorf("%s: error expectancy doesn't match: expected %v, got %v", name, test.expectedError, err)
		}

		if test.expectedError != nil {
			continue
		}

		if vertex != test.vertex {
			t.Errorf("%s: vertex expectancy doesn't match: expected %v, got %v", name, test.vertex, vertex)
		}
	}
}

func TestUndirected_AddEdge(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edges         []Edge[int]
		traits        *Traits
		expectedEdges []Edge[int]
		// Even though some AddVertex calls might work, at least one of them
		// could fail, e.g. if the last call would introduce a cycle.
		finallyExpectedError error
	}{
		"graph with 2 edges": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2, Properties: EdgeProperties{Weight: 10}},
				{Source: 1, Target: 3, Properties: EdgeProperties{Weight: 20}},
			},
			traits: &Traits{},
			expectedEdges: []Edge[int]{
				{Source: 1, Target: 2, Properties: EdgeProperties{Weight: 10}},
				{Source: 1, Target: 3, Properties: EdgeProperties{Weight: 20}},
			},
		},
		"hashes for non-existent vertices": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{Source: 1, Target: 3, Properties: EdgeProperties{Weight: 20}},
			},
			traits:               &Traits{},
			finallyExpectedError: ErrVertexNotFound,
		},
		"edge introducing a cycle in an acyclic graph": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 2, Target: 3},
				{Source: 3, Target: 1},
			},
			traits: &Traits{
				PreventCycles: true,
			},
			finallyExpectedError: ErrEdgeCreatesCycle,
		},
		"edge already exists": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 2, Target: 3},
				{Source: 3, Target: 1},
				{Source: 3, Target: 1},
			},
			traits:               &Traits{},
			finallyExpectedError: ErrEdgeAlreadyExists,
		},
		"edge with attributes": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
			},
			expectedEdges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
			},
			traits: &Traits{},
		},
		"edge with data": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Data: "foo",
					},
				},
			},
			expectedEdges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Data: "foo",
					},
				},
			},
			traits: &Traits{},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, test.traits, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		var err error

		for _, edge := range test.edges {
			if len(edge.Properties.Attributes) == 0 {
				err = graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight), EdgeData(edge.Properties.Data))
			}
			// If there are vertex attributes, iterate over them and call the
			// VertexAttribute functional option for each entry. A vertex should
			// only have one attribute so that AddVertex is invoked once.
			for key, value := range edge.Properties.Attributes {
				err = graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight), EdgeData(edge.Properties.Data), EdgeAttribute(key, value))
			}
			if err != nil {
				break
			}
		}

		if !errors.Is(err, test.finallyExpectedError) {
			t.Fatalf("%s: error expectancy doesn't match: expected %v, got %v", name, test.finallyExpectedError, err)
		}

		for _, expectedEdge := range test.expectedEdges {
			sourceHash := graph.hash(expectedEdge.Source)
			targetHash := graph.hash(expectedEdge.Target)

			edge, ok := graph.store.(*memoryStore[int, int]).outEdges[sourceHash][targetHash]
			if !ok {
				t.Fatalf("%s: edge with source %v and target %v not found", name, expectedEdge.Source, expectedEdge.Target)
			}

			if !edgesAreEqual(expectedEdge, edge, false) {
				t.Errorf("%s: expected edge %v, got %v", name, expectedEdge, edge)
			}
		}
	}
}

func TestUndirected_AddEdgesFrom(t *testing.T) {
	tests := map[string]struct {
		vertices         []int
		edges            []Edge[int]
		existingVertices []int
		existingEdges    []Edge[int]
		expectedEdges    []Edge[int]
		expectedError    error
	}{
		"graph with 3 edges": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Weight: 10,
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
				{
					Source: 2,
					Target: 3,
					Properties: EdgeProperties{
						Weight: 20,
						Attributes: map[string]string{
							"color": "green",
						},
					},
				},
				{
					Source: 3,
					Target: 1,
					Properties: EdgeProperties{
						Weight: 30,
						Attributes: map[string]string{
							"color": "blue",
						},
					},
				},
			},
			existingVertices: []int{1, 2, 3},
			existingEdges:    []Edge[int]{},
			expectedEdges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Weight: 10,
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
				{
					Source: 2,
					Target: 3,
					Properties: EdgeProperties{
						Weight: 20,
						Attributes: map[string]string{
							"color": "green",
						},
					},
				},
				{
					Source: 3,
					Target: 1,
					Properties: EdgeProperties{
						Weight: 30,
						Attributes: map[string]string{
							"color": "blue",
						},
					},
				},
			},
			expectedError: nil,
		},
		"edge with non-existing vertex": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 3},
			},
			existingVertices: []int{1, 2},
			existingEdges:    []Edge[int]{},
			expectedEdges:    []Edge[int]{},
			expectedError:    ErrVertexNotFound,
		},
		"graph with duplicated edge": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
			},
			existingVertices: []int{1, 2},
			existingEdges: []Edge[int]{
				{Source: 1, Target: 2},
			},
			expectedEdges: []Edge[int]{},
			expectedError: ErrEdgeAlreadyExists,
		},
	}

	for name, test := range tests {
		t.Run(name, func(t *testing.T) {
			source := New(IntHash)

			for _, vertex := range test.vertices {
				_ = source.AddVertex(vertex)
			}

			for _, edge := range test.edges {
				_ = source.AddEdge(copyEdge(edge))
			}

			g := New(IntHash)

			for _, vertex := range test.existingVertices {
				_ = g.AddVertex(vertex)
			}

			for _, edge := range test.existingEdges {
				_ = g.AddEdge(copyEdge(edge))
			}

			err := g.AddEdgesFrom(source)

			if !errors.Is(err, test.expectedError) {
				t.Fatalf("expected error %v, got %v", test.expectedError, err)
			}

			for _, edge := range test.expectedEdges {
				actualEdge, err := g.Edge(edge.Source, edge.Target)
				if err != nil {
					t.Fatalf("failed to get edge (%v, %v): %v", edge.Source, edge.Target, err.Error())
				}

				if !edgesAreEqual(edge, actualEdge, false) {
					t.Errorf("%s: expected edge %v, got %v", name, edge, actualEdge)
				}
			}
		})
	}
}

func TestUndirected_RemoveVertex(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edges         []Edge[int]
		vertex        int
		expectedError error
	}{
		"existing disconnected vertex": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 2, Target: 3},
			},
			vertex: 1,
		},
		"existing connected vertex": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 2, Target: 3},
			},
			vertex:        1,
			expectedError: ErrVertexHasEdges,
		},
		"non-existent vertex": {
			vertices:      []int{1, 2, 3},
			edges:         []Edge[int]{},
			vertex:        4,
			expectedError: ErrVertexNotFound,
		},
	}

	for name, test := range tests {
		graph := New(IntHash)

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			_ = graph.AddEdge(edge.Source, edge.Target)
		}

		err := graph.RemoveVertex(test.vertex)

		if !errors.Is(err, test.expectedError) {
			t.Errorf("%s: error expectancy doesn't match: expected %v, got %v", name, test.expectedError, err)
		}
	}
}

func TestUndirected_Edge(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edge          Edge[int]
		args          [2]int
		expectedError error
	}{
		"get edge of undirected graph": {
			vertices: []int{1, 2, 3},
			edge:     Edge[int]{Source: 1, Target: 2},
			args:     [2]int{1, 2},
		},
		"get edge of undirected graph with swapped source and target": {
			vertices: []int{1, 2, 3},
			edge:     Edge[int]{Source: 1, Target: 2},
			args:     [2]int{2, 1},
		},
		"get non-existent edge of undirected graph": {
			vertices:      []int{1, 2, 3},
			edge:          Edge[int]{Source: 1, Target: 2},
			args:          [2]int{2, 3},
			expectedError: ErrEdgeNotFound,
		},
		"get edge with properties": {
			vertices: []int{1, 2, 3},
			edge: Edge[int]{
				Source: 1,
				Target: 2,
				Properties: EdgeProperties{
					// Attributes can't be tested at the moment, because there
					// is no way to add multiple attributes at once (using a
					// functional option like EdgeAttributes).
					// ToDo: Add Attributes once EdgeAttributes exists.
					Attributes: map[string]string{},
					Weight:     10,
					Data:       "this is an edge",
				},
			},
			args: [2]int{1, 2},
		},
	}

	for name, test := range tests {
		graph := New(IntHash)

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		if err := graph.AddEdge(test.edge.Source, test.edge.Target, EdgeWeight(test.edge.Properties.Weight), EdgeData(test.edge.Properties.Data)); err != nil {
			t.Fatalf("%s: failed to add edge: %s", name, err.Error())
		}

		edge, err := graph.Edge(test.args[0], test.args[1])

		if !errors.Is(err, test.expectedError) {
			t.Fatalf("%s: error expectancy doesn't match: expected %v, got %v", name, test.expectedError, err)
		}

		if test.expectedError != nil {
			continue
		}

		if edge.Source != test.args[0] {
			t.Errorf("%s: source expectancy doesn't match: expected %v, got %v", name, test.args[0], edge.Source)
		}

		if edge.Target != test.args[1] {
			t.Errorf("%s: target expectancy doesn't match: expected %v, got %v", name, test.args[1], edge.Target)
		}

		if !edgesAreEqual(test.edge, edge, false) {
			t.Errorf("%s: expected edge %v, got %v", name, test.edge, edge)
		}
	}
}

func TestUndirected_Edges(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edges         []Edge[int]
		expectedEdges []Edge[int]
	}{
		"graph with 3 edges": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Weight: 10,
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
				{
					Source: 2,
					Target: 3,
					Properties: EdgeProperties{
						Weight: 20,
						Attributes: map[string]string{
							"color": "green",
						},
					},
				},
				{
					Source: 3,
					Target: 1,
					Properties: EdgeProperties{
						Weight: 30,
						Attributes: map[string]string{
							"color": "blue",
						},
					},
				},
			},
			expectedEdges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Weight: 10,
						Attributes: map[string]string{
							"color": "red",
						},
					},
				},
				{
					Source: 2,
					Target: 3,
					Properties: EdgeProperties{
						Weight: 20,
						Attributes: map[string]string{
							"color": "green",
						},
					},
				},
				{
					Source: 3,
					Target: 1,
					Properties: EdgeProperties{
						Weight: 30,
						Attributes: map[string]string{
							"color": "blue",
						},
					},
				},
			},
		},
	}

	for name, test := range tests {
		t.Run(name, func(t *testing.T) {
			g := New(IntHash)

			for _, vertex := range test.vertices {
				_ = g.AddVertex(vertex)
			}

			for _, edge := range test.edges {
				_ = g.AddEdge(copyEdge(edge))
			}

			edges, err := g.Edges()
			if err != nil {
				t.Fatalf("unexpected error: %v", err.Error())
			}

			for _, expectedEdge := range test.expectedEdges {
				for _, actualEdge := range edges {
					if actualEdge.Source != expectedEdge.Source || actualEdge.Target != expectedEdge.Target {
						continue
					}
					if !edgesAreEqual(expectedEdge, actualEdge, false) {
						t.Errorf("%s: expected edge %v, got %v", name, expectedEdge, actualEdge)
					}
				}
			}
		})
	}
}

func TestUndirected_UpdateEdge(t *testing.T) {
	tests := map[string]struct {
		vertices    []int
		edges       []Edge[int]
		updateEdge  Edge[int]
		expectedErr error
	}{
		"update an edge": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{
					Source: 1,
					Target: 2,
					Properties: EdgeProperties{
						Weight: 10,
						Attributes: map[string]string{
							"color": "red",
						},
						Data: "my-edge",
					},
				},
			},
			updateEdge: Edge[int]{
				Source: 1,
				Target: 2,
				Properties: EdgeProperties{
					Weight: 20,
					Attributes: map[string]string{
						"color": "blue",
						"label": "a blue edge",
					},
					Data: "my-updated-edge",
				},
			},
		},
	}

	for name, test := range tests {
		t.Run(name, func(t *testing.T) {
			g := New(IntHash)

			for _, vertex := range test.vertices {
				_ = g.AddVertex(vertex)
			}

			for _, edge := range test.edges {
				_ = g.AddEdge(copyEdge(edge))
			}

			err := g.UpdateEdge(copyEdge(test.updateEdge))

			if !errors.Is(err, test.expectedErr) {
				t.Fatalf("expected error %v, got %v", test.expectedErr, err)
			}

			actualEdge, err := g.Edge(test.updateEdge.Source, test.updateEdge.Target)
			if err != nil {
				t.Fatalf("unexpected error: %v", err.Error())
			}

			if !edgesAreEqual(test.updateEdge, actualEdge, false) {
				t.Errorf("expected edge %v, got %v", test.updateEdge, actualEdge)
			}
		})
	}
}

func TestUndirected_RemoveEdge(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edges         []Edge[int]
		removeEdges   []Edge[int]
		expectedError error
	}{
		"two-vertices graph": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
			},
			removeEdges: []Edge[int]{
				{Source: 1, Target: 2},
			},
		},
		"remove 2 edges from triangle": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
			},
			removeEdges: []Edge[int]{
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
			},
		},
		"remove non-existent edge": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
			},
			removeEdges: []Edge[int]{
				{Source: 2, Target: 3},
			},
			// Expect no error because memoryStore doesn't error
		},
	}

	for name, test := range tests {
		graph := New(IntHash)

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight)); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		for _, removeEdge := range test.removeEdges {
			if err := graph.RemoveEdge(removeEdge.Source, removeEdge.Target); !errors.Is(err, test.expectedError) {
				t.Errorf("%s: error expectancy doesn't match: expected %v, got %v", name, test.expectedError, err)
			}
			// After removing the edge, verify that it can't be retrieved using
			// Edge anymore.
			if _, err := graph.Edge(removeEdge.Source, removeEdge.Target); !errors.Is(err, ErrEdgeNotFound) {
				t.Fatalf("%s: error expectancy doesn't match: expected %v, got %v", name, ErrEdgeNotFound, err)
			}
		}
	}
}

func TestUndirected_Adjacencies(t *testing.T) {
	tests := map[string]struct {
		vertices []int
		edges    []Edge[int]
		expected map[int]map[int]Edge[int]
	}{
		"Y-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
				{Source: 3, Target: 4},
			},
			expected: map[int]map[int]Edge[int]{
				1: {
					3: {Source: 1, Target: 3},
				},
				2: {
					3: {Source: 2, Target: 3},
				},
				3: {
					1: {Source: 3, Target: 1},
					2: {Source: 3, Target: 2},
					4: {Source: 3, Target: 4},
				},
				4: {
					3: {Source: 4, Target: 3},
				},
			},
		},
		"diamond-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 3, Target: 4},
			},
			expected: map[int]map[int]Edge[int]{
				1: {
					2: {Source: 1, Target: 2},
					3: {Source: 1, Target: 3},
				},
				2: {
					1: {Source: 2, Target: 1},
					4: {Source: 2, Target: 4},
				},
				3: {
					1: {Source: 3, Target: 1},
					4: {Source: 3, Target: 4},
				},
				4: {
					2: {Source: 4, Target: 2},
					3: {Source: 4, Target: 3},
				},
			},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight)); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		adjacencyMap, _ := graph.AdjacencyMap()

		for expectedVertex, expectedAdjacencies := range test.expected {
			adjacencies, ok := adjacencyMap[expectedVertex]
			if !ok {
				t.Errorf("%s: expected vertex %v does not exist in adjacency map", name, expectedVertex)
			}

			for expectedAdjacency, expectedEdge := range expectedAdjacencies {
				edge, ok := adjacencies[expectedAdjacency]
				if !ok {
					t.Errorf("%s: expected adjacency %v does not exist in map of %v", name, expectedAdjacency, expectedVertex)
				}
				if edge.Source != expectedEdge.Source || edge.Target != expectedEdge.Target {
					t.Errorf("%s: edge expectancy doesn't match: expected %v, got %v", name, expectedEdge, edge)
				}
			}
		}
	}
}

func TestUndirected_PredecessorMap(t *testing.T) {
	tests := map[string]struct {
		vertices []int
		edges    []Edge[int]
		expected map[int]map[int]Edge[int]
	}{
		"Y-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
				{Source: 3, Target: 4},
			},
			expected: map[int]map[int]Edge[int]{
				1: {
					3: {Source: 1, Target: 3},
				},
				2: {
					3: {Source: 2, Target: 3},
				},
				3: {
					1: {Source: 3, Target: 1},
					2: {Source: 3, Target: 2},
					4: {Source: 3, Target: 4},
				},
				4: {
					3: {Source: 4, Target: 3},
				},
			},
		},
		"diamond-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 3, Target: 4},
			},
			expected: map[int]map[int]Edge[int]{
				1: {
					2: {Source: 1, Target: 2},
					3: {Source: 1, Target: 3},
				},
				2: {
					1: {Source: 2, Target: 1},
					4: {Source: 2, Target: 4},
				},
				3: {
					1: {Source: 3, Target: 1},
					4: {Source: 3, Target: 4},
				},
				4: {
					2: {Source: 4, Target: 2},
					3: {Source: 4, Target: 3},
				},
			},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight)); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		predecessors, _ := graph.PredecessorMap()

		for expectedVertex, expectedPredecessors := range test.expected {
			predecessors, ok := predecessors[expectedVertex]
			if !ok {
				t.Errorf("%s: expected vertex %v does not exist in adjacency map", name, expectedVertex)
			}

			for expectedPredecessor, expectedEdge := range expectedPredecessors {
				edge, ok := predecessors[expectedPredecessor]
				if !ok {
					t.Errorf("%s: expected adjacency %v does not exist in map of %v", name, expectedPredecessor, expectedVertex)
				}
				if edge.Source != expectedEdge.Source || edge.Target != expectedEdge.Target {
					t.Errorf("%s: edge expectancy doesn't match: expected %v, got %v", name, expectedEdge, edge)
				}
			}
		}
	}
}

func TestUndirected_Clone(t *testing.T) {
	tests := map[string]struct {
		vertices []int
		edges    []Edge[int]
	}{
		"Y-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
				{Source: 3, Target: 4},
			},
		},
		"diamond-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 3, Target: 4},
			},
		},
	}

	for name, test := range tests {
		graph := New(IntHash)

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex, VertexWeight(vertex), VertexAttribute("color", "red"))
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight)); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		clonedGraph, err := graph.Clone()
		if err != nil {
			t.Fatalf("%s: failed to clone graph: %s", name, err.Error())
		}

		expected := graph.(*undirected[int, int])
		actual := clonedGraph.(*undirected[int, int])

		if actual.hash(5) != expected.hash(5) {
			t.Errorf("%s: hash expectancy doesn't match: expected %v, got %v", name, expected.hash, actual.hash)
		}

		if !traitsAreEqual(actual.traits, expected.traits) {
			t.Errorf("%s: traits expectancy doesn't match: expected %v, got %v", name, expected.traits, actual.traits)
		}

		expectedAdjacencyMap, _ := graph.AdjacencyMap()
		actualAdjacencyMap, _ := actual.AdjacencyMap()

		if !adjacencyMapsAreEqual(expectedAdjacencyMap, actualAdjacencyMap, expected.edgesAreEqual) {
			t.Errorf("%s: expected adjacency map %v, got %v", name, expectedAdjacencyMap, actualAdjacencyMap)
		}

		_ = clonedGraph.AddVertex(10)

		if _, err := graph.Vertex(10); err == nil {
			t.Errorf("%s: vertex 10 shouldn't exist in original graph", name)
		}
	}
}

func TestUndirected_OrderAndSize(t *testing.T) {
	tests := map[string]struct {
		vertices      []int
		edges         []Edge[int]
		expectedOrder int
		expectedSize  int
	}{
		"Y-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 3},
				{Source: 2, Target: 3},
				{Source: 3, Target: 4},
			},
			expectedOrder: 4,
			expectedSize:  3,
		},
		"diamond-shaped graph": {
			vertices: []int{1, 2, 3, 4},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 3, Target: 4},
			},
			expectedOrder: 4,
			expectedSize:  4,
		},
		"two-vertices graph": {
			vertices: []int{1, 2},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
			},
			expectedOrder: 2,
			expectedSize:  1,
		},
		"edgeless graph": {
			vertices:      []int{1, 2},
			edges:         []Edge[int]{},
			expectedOrder: 2,
			expectedSize:  0,
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target, EdgeWeight(edge.Properties.Weight)); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		order, _ := graph.Order()
		size, _ := graph.Size()

		if order != test.expectedOrder {
			t.Errorf("%s: order expectancy doesn't match: expected %d, got %d", name, test.expectedOrder, order)
		}

		if size != test.expectedSize {
			t.Errorf("%s: size expectancy doesn't match: expected %d, got %d", name, test.expectedSize, size)
		}

	}
}

func TestUndirected_edgesAreEqual(t *testing.T) {
	tests := map[string]struct {
		a             Edge[int]
		b             Edge[int]
		edgesAreEqual bool
	}{
		"equal edges in undirected graph": {
			a:             Edge[int]{Source: 1, Target: 2},
			b:             Edge[int]{Source: 1, Target: 2},
			edgesAreEqual: true,
		},
		"swapped equal edges in undirected graph": {
			a:             Edge[int]{Source: 1, Target: 2},
			b:             Edge[int]{Source: 2, Target: 1},
			edgesAreEqual: true,
		},
		"unequal edges in undirected graph": {
			a: Edge[int]{Source: 1, Target: 2},
			b: Edge[int]{Source: 1, Target: 3},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())
		actual := graph.edgesAreEqual(test.a, test.b)

		if actual != test.edgesAreEqual {
			t.Errorf("%s: equality expectations don't match: expected %v, got %v", name, test.edgesAreEqual, actual)
		}
	}
}

func TestUndirected_addEdge(t *testing.T) {
	tests := map[string]struct {
		edges []Edge[int]
	}{
		"add 3 edges": {
			edges: []Edge[int]{
				{Source: 1, Target: 2, Properties: EdgeProperties{Weight: 1}},
				{Source: 2, Target: 3, Properties: EdgeProperties{Weight: 2}},
				{Source: 3, Target: 1, Properties: EdgeProperties{Weight: 3}},
			},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, edge := range test.edges {
			_ = graph.AddVertex(edge.Source)
			_ = graph.AddVertex(edge.Target)
			sourceHash := graph.hash(edge.Source)
			TargetHash := graph.hash(edge.Target)
			err := graph.addEdge(sourceHash, TargetHash, edge)
			if err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		outEdges := graph.store.(*memoryStore[int, int]).outEdges
		if len(outEdges) != len(test.edges) {
			t.Errorf("%s: number of outgoing edges doesn't match: expected %v, got %v", name, len(test.edges), len(outEdges))
		}
		inEdges := graph.store.(*memoryStore[int, int]).inEdges
		if len(inEdges) != len(test.edges) {
			t.Errorf("%s: number of ingoing edges doesn't match: expected %v, got %v", name, len(test.edges), len(inEdges))
		}
	}
}

func TestUndirected_adjacencies(t *testing.T) {
	tests := map[string]struct {
		vertices             []int
		edges                []Edge[int]
		vertex               int
		expectedAdjancencies []int
	}{
		"graph with 3 vertices": {
			vertices: []int{1, 2, 3},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
			},
			vertex:               2,
			expectedAdjancencies: []int{1},
		},
		"graph with 6 vertices": {
			vertices: []int{1, 2, 3, 4, 5, 6},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 2, Target: 5},
				{Source: 3, Target: 6},
			},
			vertex:               2,
			expectedAdjancencies: []int{1, 4, 5},
		},
		"graph with 7 vertices and a diamond cycle (#1)": {
			vertices: []int{1, 2, 3, 4, 5, 6, 7},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 2, Target: 5},
				{Source: 3, Target: 6},
				{Source: 4, Target: 7},
				{Source: 5, Target: 7},
			},
			vertex:               5,
			expectedAdjancencies: []int{2, 7},
		},
		"graph with 7 vertices and a diamond cycle (#2)": {
			vertices: []int{1, 2, 3, 4, 5, 6, 7},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 2, Target: 5},
				{Source: 3, Target: 6},
				{Source: 4, Target: 7},
				{Source: 5, Target: 7},
			},
			vertex:               7,
			expectedAdjancencies: []int{4, 5},
		},
		"graph with 7 vertices and a diamond cycle (#3)": {
			vertices: []int{1, 2, 3, 4, 5, 6, 7},
			edges: []Edge[int]{
				{Source: 1, Target: 2},
				{Source: 1, Target: 3},
				{Source: 2, Target: 4},
				{Source: 2, Target: 5},
				{Source: 3, Target: 6},
				{Source: 4, Target: 7},
				{Source: 5, Target: 7},
			},
			vertex:               2,
			expectedAdjancencies: []int{1, 4, 5},
		},
	}

	for name, test := range tests {
		graph := newUndirected(IntHash, &Traits{}, newMemoryStore[int, int]())

		for _, vertex := range test.vertices {
			_ = graph.AddVertex(vertex)
		}

		for _, edge := range test.edges {
			if err := graph.AddEdge(edge.Source, edge.Target); err != nil {
				t.Fatalf("%s: failed to add edge: %s", name, err.Error())
			}
		}

		adjacencyList := adjacencyList(graph.store, graph.hash(test.vertex))

		if !slicesAreEqual(adjacencyList, test.expectedAdjancencies) {
			t.Errorf("%s: adjacencies don't match: expected %v, got %v", name, test.expectedAdjancencies, adjacencyList)
		}
	}
}

func adjacencyList[K comparable, T any](store Store[K, T], vertexHash K) []K {
	var adjacencyHashes []K

	// An undirected graph creates an undirected edge as two directed edges in
	// the opposite direction, so both the in-edges and the out-edges work here.
	inEdges, ok := store.(*memoryStore[K, T]).inEdges[vertexHash]
	if !ok {
		return adjacencyHashes
	}

	for hash := range inEdges {
		adjacencyHashes = append(adjacencyHashes, hash)
	}

	return adjacencyHashes
}