Secondary variants are variants created via the Configuration#getOutgoing(): ConfigurationPublications API which also participate in selection, in addition to the configuration itself.

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        if (attributes.isEmpty()) {
            failWith("Variant '" + name + "' must declare at least one attribute.");
        }
        if (variants.containsKey(name)) {
            failWith("It is invalid to have multiple variants with the same name ('" + name + "')");
        } else {
            VariantIdentity identity = new VariantIdentity(attributes, capabilities);
            if (variants.containsValue(identity)) {

        publishedModule.parsedPom.scopes.isEmpty()
        publishedModule.parsedModuleMetadata.variants*.name == ["usage"]
        with(publishedModule.parsedModuleMetadata.variant("usage")) { variant ->
            variant.files.empty
            variant.dependencies.empty
            variant.availableAt.coords == 'org.gradle.test:nested:1.9-SNAPSHOT'
            variant.availableAt.url == "../../nested/1.9-SNAPSHOT/nested-1.9-SNAPSHOT.module"
        }

 * <p>You can use this interface to associate artifacts with a configuration using the {@link #artifact(Object)} methods. You can also define several variants of the configuration's artifacts. Each variant represents a set of artifacts that form some mutually exclusive usage of the component.</p>
 *
 * <p>An implicit variant is defined for a configuration whenever any artifacts are attached directly to this object or inherited from another configuration.</p>
 *

        }
        variants.get(outgoingConfiguration).addAction(action);
    }

    @Override
    public Set<? extends UsageContext> getUsages() {
        if (cachedVariants == null) {
            ImmutableSet.Builder<UsageContext> builder = new ImmutableSet.Builder<>();

swift-library-variant-task-graph.png...

cpp-library-variant-task-graph.png...

  compileTestVariantCpp -> linkTestVariant -> installTestVariant -> runTestVariant [dir=back, style=dashed]
  compileTestVariantCpp[label=<compile<i>Variant</i>Cpp>]
  linkTestVariant[label=<link<i>Variant</i>>]
  installTestVariant[label=<installTest<i>Variant</i>>]
  runTestVariant[label=<runTest<i>Variant</i>>]

        then: "the result should have the variant added by the rule"
        def variantsForGraphTraversal = result.variantsForGraphTraversal
        variantsForGraphTraversal.size() == ownVariants + 1
        def variant = variantsForGraphTraversal.find { it.name == "test" }
        variant != null
        "org.gradle.test" in variant.attributes.keySet().collect { it.name }

        where:

    @Override
    public Set<? extends SoftwareComponent> getVariants() {
        return variants;
    }

    public void addArtifact(PublishArtifact artifact) {
        artifacts.add(artifact);
    }

    /**
     * Adds a child variant
     */
    public void addVariant(SoftwareComponent variant) {
        variants.add(variant);
    }