// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using AwesomeAssertions;

using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.Execution;
using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter.ObjectModel;
using Microsoft.VisualStudio.TestTools.UnitTesting;

using TestFramework.ForTestingMSTest;

using ExecutionScope = Microsoft.VisualStudio.TestTools.UnitTesting.ExecutionScope;

namespace MSTestAdapter.PlatformServices.UnitTests.Execution;

public sealed class TestDependencyGraphTests : TestContainer
{
    private const string ClassA = "Ns.ClassA";
    private const string ClassB = "Ns.ClassB";

    private static UnitTestElement CreateElement(string className, string methodName, params TestDependencyInfo[] dependencies)
        => new(new TestMethod(methodName, className, "DummyAssembly", displayName: null))
        {
            Dependencies = dependencies.Length == 0 ? null : dependencies,
        };

    private static TestDependencyInfo DependsOnMethod(string methodName, bool proceedOnFailure = false)
        => new(null, methodName, proceedOnFailure);

    private static TestDependencyInfo DependsOnClass(string className)
        => new(className, null, proceedOnFailure: false);

    private static string[] NamesOf(IEnumerable<UnitTestElement> elements)
        => [.. elements.Select(e => e.TestMethod.Name)];

    private static string[] NamesOfBroken(IEnumerable<TestDependencyGraph.BrokenTest> broken)
        => [.. broken.Select(b => b.Element.TestMethod.Name)];

    public void Build_WhenNoTestDeclaresDependencies_ReturnsNull()
    {
        // The null fast path is what keeps every run that does not use the feature on the code it uses today.
        var graph = TestDependencyGraph.Build(
            [CreateElement(ClassA, "A"), CreateElement(ClassA, "B")],
            ExecutionScope.MethodLevel,
            parallelizationEnabled: true);

        graph.Should().BeNull();
    }

    public void Build_OrdersDependentAfterItsPrerequisiteWithinAChunk()
    {
        // Declared in reverse order on purpose: only the dependency, not the declaration order, may decide.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "Second", DependsOnMethod("First")),
            CreateElement(ClassA, "First"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        graph.ParallelChunks.Should().ContainSingle();
        NamesOf(graph.ParallelChunks[0]).Should().Equal("First", "Second");
        graph.Errors.Should().BeEmpty();
    }

    public void Build_UnderClassLevelScope_MakesTheDependentClassWaitForThePrerequisiteClass()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassB, "NeedsA", new TestDependencyInfo(ClassA, "Setup", false)),
            CreateElement(ClassA, "Setup"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        graph.ParallelChunks.Length.Should().Be(2);
        int classBChunk = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.FullClassName == ClassB);
        int classAChunk = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.FullClassName == ClassA);

        graph.ParallelChunkPrerequisites[classBChunk].Should().Equal(classAChunk);
        graph.ParallelChunkPrerequisites[classAChunk].Should().BeEmpty();
    }

    public void Build_WhenTwoTestsShareAPrerequisite_LeavesThemIndependentSoTheyCanRunInParallel()
    {
        // Fan-out is the whole point of a graph over a flat order: neither branch may wait for the other.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "Root"),
            CreateElement(ClassA, "BranchOne", DependsOnMethod("Root")),
            CreateElement(ClassA, "BranchTwo", DependsOnMethod("Root")),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        int root = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "Root");
        int one = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "BranchOne");
        int two = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "BranchTwo");

        graph.ParallelChunkPrerequisites[one].Should().Equal(root);
        graph.ParallelChunkPrerequisites[two].Should().Equal(root);
        graph.ParallelChunkPrerequisites[one].Should().NotContain(two);
        graph.ParallelChunkPrerequisites[two].Should().NotContain(one);
    }

    public void Build_WhenDependencyTargetsAWholeClass_WaitsForEveryTestOfThatClass()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassB, "Dependent", DependsOnClass(ClassA)),
            CreateElement(ClassA, "One"),
            CreateElement(ClassA, "Two"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.TestPrerequisites[0].Should().BeEquivalentTo([1, 2]);
    }

    public void Build_WhenAClassDependsOnItself_DoesNotCreateASelfEdge()
    {
        // A whole-class dependency naturally covers the declaring test too; treating that as a cycle would
        // make the common "this class runs after that class" declaration unusable from a base class.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "One", DependsOnClass(ClassA)),
            CreateElement(ClassA, "Two", DependsOnClass(ClassA)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        // Neither test waits for itself...
        graph.TestPrerequisites[0].Should().NotContain(0);
        graph.TestPrerequisites[1].Should().NotContain(1);

        // ...but the edges to the *other* tests of the class survive. Asserting only the absence above would
        // still hold if the suppression had deleted every edge, which is the more likely way to get this
        // wrong: over-deleting silently discards the declaration.
        graph.TestPrerequisites[0].Should().Equal(1);
        graph.TestPrerequisites[1].Should().Equal(0);

        // And because each now waits for the other, this particular declaration is a genuine mutual cycle -
        // which is the correct outcome, not something the self-edge suppression should have hidden.
        NamesOfBroken(graph.BrokenTests).Should().BeEquivalentTo(["One", "Two"]);
    }

    public void Build_WhenDependenciesFormACycle_ReportsItAndMarksTheTestsBroken()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "One", DependsOnMethod("Two")),
            CreateElement(ClassA, "Two", DependsOnMethod("One")),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Errors.Should().ContainSingle();
        graph.Errors[0].Should().Contain("One").And.Contain("Two");
        NamesOfBroken(graph.BrokenTests).Should().BeEquivalentTo(["One", "Two"]);

        // Broken tests are reported as failed instead of being scheduled, so they must not appear anywhere.
        graph.ParallelChunks.Should().BeEmpty();
        graph.SequentialTests.Should().BeEmpty();
    }

    public void Build_WhenATestDependsOnItselfByName_IsReportedAsACycle()
    {
        UnitTestElement[] tests = [CreateElement(ClassA, "Loop", DependsOnMethod("Loop"))];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Errors.Should().ContainSingle();
        NamesOfBroken(graph.BrokenTests).Should().Equal("Loop");
    }

    public void Build_WhenACycleExistsOnlyInTheClassLevelProjection_RunsTheAffectedTestsSequentiallyInOrder()
    {
        // No test depends on itself, but class A must precede B *and* B must precede A, which cannot hold
        // when the class is the scheduling unit. Dropping the ordering would be worse than losing the
        // parallelism: the run-time gate cannot tell "has not run yet" from "did not pass", so unordered
        // dependents would be skipped nondeterministically while the run still reported success.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A1"),
            CreateElement(ClassA, "A2", new TestDependencyInfo(ClassB, "B1", false)),
            CreateElement(ClassB, "B1", new TestDependencyInfo(ClassA, "A1", false)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        // A recovered downgrade, not a fatal error: the declared order is still honoured, so this must not
        // land on Errors, which is what stamps a failure message onto tests caught in a real cycle.
        graph.Errors.Should().BeEmpty();
        graph.Warnings.Should().ContainSingle();
        graph.Warnings[0].Should().Contain("MethodLevel");

        // The test-level graph is sound, so nothing is broken - the tests still run.
        graph.BrokenTests.Should().BeEmpty();

        // They are moved to the sequential phase, where the topological order is honoured exactly.
        graph.ParallelChunks.Should().BeEmpty();
        NamesOf(graph.SequentialTests).Should().Equal("A1", "B1", "A2");
    }

    public void Build_WhenCyclesOverlap_MarksEveryMemberOfBothCycles()
    {
        // A depends on B and C; B on A; C on B. There are two overlapping cycles - A>B>A and C>B>A>C - and
        // every one of the three tests is in one. A plain depth-first search reports whichever back edge it
        // closes first (A>B>A), finishes B, and then never notices C is cyclic too, leaving C scheduled. Only
        // a component-based pass finds all three.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A", DependsOnMethod("B"), DependsOnMethod("C")),
            CreateElement(ClassA, "B", DependsOnMethod("A")),
            CreateElement(ClassA, "C", DependsOnMethod("B")),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        NamesOfBroken(graph.BrokenTests).Should().BeEquivalentTo(["A", "B", "C"]);

        // All three are in one strongly connected component, so they share a single description. The message
        // renders one real cycle path (A > B > A here), which need not name every member - membership is
        // asserted above. Comparing against the single error is what catches a member being handed a
        // different, or an unrelated cycle's, description.
        graph.Errors.Should().ContainSingle();
        foreach (TestDependencyGraph.BrokenTest broken in graph.BrokenTests)
        {
            broken.CycleMessage.Should().Be(graph.Errors[0]);
        }

        // Nothing cyclic may be scheduled.
        graph.ParallelChunks.Should().BeEmpty();
        graph.SequentialTests.Should().BeEmpty();
    }

    public void Build_WhenCyclesOverlap_ReportsOnlyDeclaredEdgesInThePath()
    {
        // The component is {A, B, C}, but B has no edge to C. Rendering the component as a path could claim
        // "A > B > C > A" and tell the user to remove a B -> C edge that was never declared. Every arrow in
        // the message has to correspond to a real prerequisite.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A", DependsOnMethod("B"), DependsOnMethod("C")),
            CreateElement(ClassA, "B", DependsOnMethod("A")),
            CreateElement(ClassA, "C", DependsOnMethod("B")),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Errors.Should().ContainSingle();

        // Declared edges, as "dependent -> prerequisite" pairs.
        var declared = new HashSet<string> { "A>B", "A>C", "B>A", "C>B" };

        string path = graph.Errors[0];
        int start = path.IndexOf(ClassA + ".", StringComparison.Ordinal);
        string[] hops = [.. path.Substring(start).Split([" > "], StringSplitOptions.None)
            .Select(h => h.Trim().Replace(ClassA + ".", string.Empty))
            .Select(h => new string([.. h.TakeWhile(char.IsLetterOrDigit)]))];

        hops.Length.Should().BeGreaterThan(2, "a cycle path needs at least two hops plus the closing repeat");
        hops[0].Should().Be(hops[^1], "the path must close on the test it started from");

        for (int i = 0; i < hops.Length - 1; i++)
        {
            declared.Should().Contain($"{hops[i]}>{hops[i + 1]}", $"the path claims a {hops[i]} -> {hops[i + 1]} edge");
        }
    }

    public void Build_WhenTwoDisjointCyclesExist_ReportsEachFailureAgainstItsOwnCycle()
    {
        // Joining every cycle description onto every failure would tell whoever is reading One's failure
        // about a cycle it has nothing to do with - the same conflation the class-level notice was moved out
        // of Errors to avoid.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "One", DependsOnMethod("Two")),
            CreateElement(ClassA, "Two", DependsOnMethod("One")),
            CreateElement(ClassB, "Three", new TestDependencyInfo(ClassB, "Four", false)),
            CreateElement(ClassB, "Four", new TestDependencyInfo(ClassB, "Three", false)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Errors.Count.Should().Be(2);
        NamesOfBroken(graph.BrokenTests).Should().BeEquivalentTo(["One", "Two", "Three", "Four"]);

        foreach (TestDependencyGraph.BrokenTest broken in graph.BrokenTests)
        {
            string name = broken.Element.TestMethod.Name;
            if (name is "One" or "Two")
            {
                broken.CycleMessage.Should().Contain("One").And.Contain("Two");
                broken.CycleMessage.Should().NotContain("Three").And.NotContain("Four");
            }
            else
            {
                broken.CycleMessage.Should().Contain("Three").And.Contain("Four");
                broken.CycleMessage.Should().NotContain("One").And.NotContain("Two");
            }
        }
    }

    public void Build_WhenAClassIsMerelyDownstreamOfAProjectionCycle_IsDemotedButNotNamedAsCyclic()
    {
        // Kahn cannot settle a chunk that is downstream of a cycle either, but saying it "depends on each
        // other" with the cycle members would be false. ClassC only depends on the cycle; it must still be
        // demoted, and must not appear in the warning.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A1"),
            CreateElement(ClassA, "A2", new TestDependencyInfo(ClassB, "B1", false)),
            CreateElement(ClassB, "B1", new TestDependencyInfo(ClassA, "A1", false)),
            CreateElement("Ns.ClassC", "C1", new TestDependencyInfo(ClassB, "B1", false)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        graph.Warnings.Should().ContainSingle();
        graph.Warnings[0].Should().Contain(ClassA).And.Contain(ClassB);
        graph.Warnings[0].Should().NotContain("ClassC");

        // Demoted all the same - it cannot run in the parallel phase once its prerequisite left it.
        NamesOf(graph.SequentialTests).Should().Contain("C1");
    }

    public void Build_WhenAClassLinksTwoProjectionCycles_IsDemotedButNotNamedAsCyclic()
    {
        // ClassX sits on a one-way path from one mutual pair to another: ClassA depends on it, and it
        // depends on ClassC. Nothing returns to ClassX, so it is in neither cycle - but it does have a
        // blocked dependent (ClassA), which is why narrowing the blocked set by peeling chunks that nothing
        // blocked depends on cannot isolate cycle membership. Both cycles keep every one of their chunks
        // from ever being peeled, so ClassX would survive and be named as mutually dependent.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A1"),
            CreateElement(ClassA, "A2", new TestDependencyInfo(ClassB, "B1", false)),
            CreateElement(ClassA, "A3", new TestDependencyInfo("Ns.ClassX", "X1", false)),
            CreateElement(ClassB, "B1", new TestDependencyInfo(ClassA, "A1", false)),
            CreateElement("Ns.ClassX", "X1", new TestDependencyInfo("Ns.ClassC", "C1", false)),
            CreateElement("Ns.ClassC", "C1"),
            CreateElement("Ns.ClassC", "C2", new TestDependencyInfo("Ns.ClassD", "D1", false)),
            CreateElement("Ns.ClassD", "D1", new TestDependencyInfo("Ns.ClassC", "C1", false)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        // No test-level cycle exists here - every cycle is created by the class-level projection.
        graph.Errors.Should().BeEmpty();

        graph.Warnings.Should().ContainSingle();
        graph.Warnings[0].Should().Contain(ClassA).And.Contain(ClassB).And.Contain("ClassC").And.Contain("ClassD");
        graph.Warnings[0].Should().NotContain("ClassX");

        // Demoted all the same: it cannot run in the parallel phase while its prerequisite chunk is
        // unschedulable there.
        NamesOf(graph.SequentialTests).Should().Contain("X1");
    }

    public void Build_WhenAProjectionCycleIsDemoted_LeavesUnrelatedTestsInTheParallelPhase()
    {
        // Only the classes caught in the projection cycle lose their parallelism; everything else keeps it.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A1"),
            CreateElement(ClassA, "A2", new TestDependencyInfo(ClassB, "B1", false)),
            CreateElement(ClassB, "B1", new TestDependencyInfo(ClassA, "A1", false)),
            CreateElement("Ns.ClassC", "C1"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        graph.ParallelChunks.Should().ContainSingle();
        NamesOf(graph.ParallelChunks[0]).Should().Equal("C1");
        NamesOf(graph.SequentialTests).Should().Equal("A1", "B1", "A2");
    }

    public void Build_WhenTheSameGraphUsesMethodLevelScope_HasNoProjectionCycle()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "A1"),
            CreateElement(ClassA, "A2", new TestDependencyInfo(ClassB, "B1", false)),
            CreateElement(ClassB, "B1", new TestDependencyInfo(ClassA, "A1", false)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Errors.Should().BeEmpty();
        graph.Warnings.Should().BeEmpty();

        // Asserting the absence of a diagnostic is not enough: it would still hold if the graph came back
        // with the wrong chunks. Under MethodLevel each test is its own chunk, so the same declarations that
        // deadlocked the class-level projection schedule cleanly, with every test still in the parallel phase
        // and the real edges preserved.
        graph.ParallelChunks.Length.Should().Be(3);
        graph.SequentialTests.Should().BeEmpty();
        graph.BrokenTests.Should().BeEmpty();

        int a1 = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "A1");
        int a2 = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "A2");
        int b1 = Array.FindIndex(graph.ParallelChunks, c => c[0].TestMethod.Name == "B1");

        graph.ParallelChunkPrerequisites[a1].Should().BeEmpty();
        graph.ParallelChunkPrerequisites[b1].Should().Equal(a1);
        graph.ParallelChunkPrerequisites[a2].Should().Equal(b1);
    }

    public void Build_WhenAPrerequisiteIsNotParallelizable_DemotesItsDependentsToTheSequentialPhase()
    {
        // The sequential phase runs after the parallel one, so a parallel test waiting on a sequential
        // prerequisite could never observe it complete. The dependent moves instead.
        UnitTestElement prerequisite = CreateElement(ClassA, "Serial");
        prerequisite.DoNotParallelize = true;

        UnitTestElement[] tests =
        [
            prerequisite,
            CreateElement(ClassA, "Direct", DependsOnMethod("Serial")),
            CreateElement(ClassB, "Transitive", new TestDependencyInfo(ClassA, "Direct", false)),
            CreateElement(ClassB, "Unrelated"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        NamesOf(graph.SequentialTests).Should().Equal("Serial", "Direct", "Transitive");
        graph.ParallelChunks.Should().ContainSingle();
        graph.ParallelChunks[0][0].TestMethod.Name.Should().Be("Unrelated");
    }

    public void Build_WhenParallelizationIsDisabled_PutsEveryTestInTheSequentialPhaseInDependencyOrder()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "Last", DependsOnMethod("Middle")),
            CreateElement(ClassA, "Middle", DependsOnMethod("First")),
            CreateElement(ClassA, "First"),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: false)!;

        graph.ParallelChunks.Should().BeEmpty();
        NamesOf(graph.SequentialTests).Should().Equal("First", "Middle", "Last");
    }

    public void Build_WhenADependencyMatchesNoTestInTheRun_WarnsAndIgnoresTheEdge()
    {
        // Running a subset (a filter, or a single test from an IDE) must stay possible, so an unmatched
        // reference cannot block the dependent.
        UnitTestElement[] tests = [CreateElement(ClassA, "Only", DependsOnMethod("FilteredOut"))];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.Warnings.Should().ContainSingle();
        graph.Warnings[0].Should().Contain("FilteredOut");
        graph.TestPrerequisites[0].Should().BeEmpty();
        graph.Errors.Should().BeEmpty();
    }

    public void Build_MergesProceedOnFailureAcrossEdges_HoldingBackWhenAnyEdgeAsksToSkip()
    {
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "First"),
            CreateElement(ClassA, "Second"),
            CreateElement(ClassA, "Mixed", DependsOnMethod("First", proceedOnFailure: true), DependsOnMethod("Second")),
            CreateElement(ClassA, "AllProceed", DependsOnMethod("First", proceedOnFailure: true), DependsOnMethod("Second", proceedOnFailure: true)),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.MethodLevel, parallelizationEnabled: true)!;

        graph.ProceedOnFailure[2].Should().BeFalse();
        graph.ProceedOnFailure[3].Should().BeTrue();
    }

    public void Build_TieBreaksReadyTestsByDeclarationOrder()
    {
        // Determinism matters: two runs of the same suite must schedule the same way.
        UnitTestElement[] tests =
        [
            CreateElement(ClassA, "Alpha"),
            CreateElement(ClassA, "Beta"),
            CreateElement(ClassA, "Gamma", DependsOnMethod("Beta")),
        ];

        TestDependencyGraph graph = TestDependencyGraph.Build(tests, ExecutionScope.ClassLevel, parallelizationEnabled: true)!;

        NamesOf(graph.ParallelChunks[0]).Should().Equal("Alpha", "Beta", "Gamma");
    }

    public void EncodeDecode_RoundTripsEveryTargetShape()
    {
        AssertRoundTrip(new TestDependencyInfo(ClassA, "Method", proceedOnFailure: false));
        AssertRoundTrip(new TestDependencyInfo(ClassA, null, proceedOnFailure: true));
        AssertRoundTrip(new TestDependencyInfo(null, "Method", proceedOnFailure: true));

        static void AssertRoundTrip(TestDependencyInfo original)
        {
            var decoded = TestDependencyInfo.Decode(TestDependencyInfo.Encode(original));
            decoded.TargetClassFullName.Should().Be(original.TargetClassFullName);
            decoded.TargetMethodName.Should().Be(original.TargetMethodName);
            decoded.ProceedOnFailure.Should().Be(original.ProceedOnFailure);
        }
    }

    public void Decode_WhenFlagIsUnrecognized_FailsClosedToSkipAndKeepsTheWholePayload()
    {
        // Proceeding past a failed prerequisite must never be the result of a decoding glitch, and the
        // payload must still name the test it was meant to name.
        var decoded = TestDependencyInfo.Decode("Ns.ClassA\nMethod");
        decoded.ProceedOnFailure.Should().BeFalse();
        decoded.TargetClassFullName.Should().Be("Ns.ClassA");
        decoded.TargetMethodName.Should().Be("Method");
    }

    public void DescribeTarget_RendersEachShapeReadably()
    {
        new TestDependencyInfo(ClassA, "Method", false).DescribeTarget().Should().Be("Ns.ClassA.Method");
        new TestDependencyInfo(ClassA, null, false).DescribeTarget().Should().Be("Ns.ClassA.*");
        new TestDependencyInfo(null, "Method", false).DescribeTarget().Should().Be("Method");
    }
}