diff options
author | gjoranv <gv@verizonmedia.com> | 2019-07-22 11:34:26 +0200 |
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committer | gjoranv <gv@verizonmedia.com> | 2019-07-22 12:42:53 +0200 |
commit | 49f480288a0f84034ac204bd52d92177ce19a9d1 (patch) | |
tree | 765d6865c57135b4f03a756daf69aa39912799b3 /container-di/src/test | |
parent | 35ded4c9dd3e6ea9c6ca9738ea1783b8d4ed8bce (diff) |
Add utility to find cycles in a directed graph.
- These classes are independent from di classes and can be used
as a tool for graphs in general.
Diffstat (limited to 'container-di/src/test')
2 files changed, 156 insertions, 0 deletions
diff --git a/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/CycleFinderTest.java b/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/CycleFinderTest.java new file mode 100644 index 00000000000..219aa6b5e8b --- /dev/null +++ b/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/CycleFinderTest.java @@ -0,0 +1,87 @@ +/* + * Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root. + */ + +package com.yahoo.container.di.componentgraph.cycle; + +import org.junit.Test; + +import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.A; +import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.B; +import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.C; +import static com.yahoo.container.di.componentgraph.cycle.CycleFinderTest.Vertices.D; +import static org.hamcrest.Matchers.contains; +import static org.hamcrest.Matchers.empty; +import static org.junit.Assert.assertThat; + +/** + * @author gjoranv + */ +public class CycleFinderTest { + + enum Vertices {A, B, C, D} + + @Test + public void graph_without_cycles_returns_no_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + graph.edge(B, C); + graph.edge(A, C); + graph.edge(D, A); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), empty()); + } + + @Test + public void graph_with_cycle_returns_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + graph.edge(B, C); + graph.edge(C, A); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), contains(A, B, C, A)); + } + + @Test + public void graph_with_self_referencing_vertex_returns_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, A); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), contains(A, A)); + } + + @Test + public void leading_nodes_are_stripped_from_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + graph.edge(B, C); + graph.edge(C, B); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), contains(B, C, B)); + } + + @Test + public void findCycle_is_idempotent_with_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, A); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), contains(A, A)); + assertThat(cycleFinder.findCycle(), contains(A, A)); + } + + @Test + public void findCycle_is_idempotent_without_cycle() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + + var cycleFinder = new CycleFinder<>(graph); + assertThat(cycleFinder.findCycle(), empty()); + assertThat(cycleFinder.findCycle(), empty()); + } + +} diff --git a/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/GraphTest.java b/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/GraphTest.java new file mode 100644 index 00000000000..588c1e30ffe --- /dev/null +++ b/container-di/src/test/java/com/yahoo/container/di/componentgraph/cycle/GraphTest.java @@ -0,0 +1,69 @@ +/* + * Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root. + */ + +package com.yahoo.container.di.componentgraph.cycle; + +import org.junit.Rule; +import org.junit.Test; +import org.junit.rules.ExpectedException; + +import static com.yahoo.container.di.componentgraph.cycle.GraphTest.Vertices.A; +import static com.yahoo.container.di.componentgraph.cycle.GraphTest.Vertices.B; +import static com.yahoo.container.di.componentgraph.cycle.GraphTest.Vertices.C; +import static org.hamcrest.CoreMatchers.is; +import static org.hamcrest.Matchers.contains; +import static org.hamcrest.Matchers.containsInAnyOrder; +import static org.hamcrest.Matchers.empty; +import static org.junit.Assert.assertThat; + +/** + * @author gjoranv + */ +public class GraphTest { + + enum Vertices {A, B, C} + + @Rule + public ExpectedException expectedException = ExpectedException.none(); + + @Test + public void vertices_and_edges_are_added_and_can_be_retrieved() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + graph.edge(B, C); + graph.edge(A, C); + + assertThat(graph.getVertices().size(), is(3)); + assertThat(graph.getAdjacent(A), containsInAnyOrder(B, C)); + assertThat(graph.getAdjacent(B), containsInAnyOrder(C)); + assertThat(graph.getAdjacent(C), empty()); + } + + @Test + public void null_vertices_are_not_allowed() { + var graph = new Graph<Vertices>(); + + expectedException.expect(IllegalArgumentException.class); + expectedException.expectMessage("Null vertices are not allowed"); + graph.edge(A, null); + } + + @Test + public void duplicate_edges_are_ignored() { + var graph = new Graph<Vertices>(); + graph.edge(A, B); + graph.edge(A, B); + + assertThat(graph.getAdjacent(A).size(), is(1)); + } + + @Test + public void self_edges_are_allowed() { + var graph = new Graph<Vertices>(); + graph.edge(A, A); + + assertThat(graph.getAdjacent(A), contains(A)); + } + +} |