def "reports imported BOM as a set of dependency constraints"() {
        def moduleC = mavenRepo.module('group', 'moduleC', '1.0').publish()
        def moduleB = mavenRepo.module('group', 'moduleB', '1.0').dependsOn(moduleC).publish()
        def moduleA = mavenRepo.module('group', 'moduleA', '2.0').dependsOn(moduleB).publish()
        mavenRepo.module('group', 'bom', '1.0')
                .hasType("pom")

    def "resolves available-at variant even if transitive dependencies are excluded"() {
        given:
        mavenHttpRepo.module('org', 'moduleB', '1.0')
            .dependsOn(mavenHttpRepo.module("org", "moduleA", "1.0"), exclusions: [[group: '*', module: '*']])
            .publish() // no Gradle Module metadata for this one because we don't support excludes on dependencies
        repository {
            'org:moduleA:1.0' {

        IvyModule moduleB = ivyRepo.module('b').dependsOn('c')
        IvyModule moduleA = ivyRepo.module('a').dependsOn('b')

        addExcludeRuleToModuleDependency(moduleA, 'b', excludePath1)
        addExcludeRuleToModuleDependency(moduleB, 'c', excludePath2)

        moduleB.publish()
        moduleC.publish()
        moduleA.publish()

        when:
        succeedsDependencyResolution()

        def module2 = registry.getModule("gradle-module-2")
        module1.allRequiredModules as List == [module1, module2]
        module2.allRequiredModules as List == [module2, module1]
    }

    def "supports cycles between optional modules"() {
        given:
        def module1Dir = createModule("module-1", properties(optional: 'gradle-optional-module,gradle-module-2'))

                runtimeOnly "org:bar"
            }
        """
        checkConfiguration("runtimeClasspath")

        when:
        module1.pom.expectGet()
        module1.artifact.expectGet()
        module2.pom.expectGet()
        module2.artifact.expectGet()

        run ":checkDeps"

        then:
        resolve.expectGraph {
            root(":", "org.test:test:1.9") {

        """

        when:
        parent.pom.expectGet()
        moduleA.pom.expectGet()
        moduleA.artifact.expectGet()
        moduleB.pom.expectGet()
        moduleB.artifact.expectGet()

        then:
        // have to run twice to trigger the failure, to parse the descriptor from the cache
        succeeds ":libs"

        given: "3 modules, where there are dependency relations such that module1 depends on module2 and module2 depends on module3"
        mavenRepo.module('org.test', 'module1', '1.0').publish()
        mavenRepo.module('org.test', 'module2', '1.0')
            .dependsOn('org.test', 'module1', '1.0')
            .publish()
        mavenRepo.module('org.test', 'module3', '1.0')

        def repo1 = server.getRemoteIvyRepo("/repo1")
        def repo2 = server.getRemoteIvyRepo("/repo2")
        def moduleA = repo1.module('group', 'projectA')
        moduleA.publish()
        def missingModuleB = repo1.module('group', 'projectB')
        def moduleB = repo2.module('group', 'projectB')
        moduleB.publish()

        and:
        buildFile << """
            repositories {
                ivy {

        //Here we add a module with Gradle metadata which defines a variant that uses the same attributes declared in the build script (format: "custom").
        //The dependency to this module is then added using the rule and thus is matched correctly.
        mavenGradleRepo.module("org.test", "moduleC").withModuleMetadata().variant("anotherVariantWithFormatCustom", [format: "custom"]).publish()

Such modules, that only have a name as module description, are called _automatic module_ that export **all** their packages and can read **all** modules on the module path.

A third case are traditional libraries that provide no module information at all -- for example `commons-cli:commons-cli:1.4`.
Gradle puts such libraries on the classpath instead of the module path.
The classpath is then treated as one module (the so called _unnamed_ module) by Java.