final Parent parent = new Parent();
        parent.setGroupId("org.apache");
        parent.setArtifactId("apache");
        parent.setVersion("1");

        assertNotNull(this.newModelResolver().resolveModel(parent.getDelegate(), new AtomicReference<>()));
        assertEquals("1", parent.getVersion());
    }

    @Test
    void testResolveParentSuccessfullyResolvesExistingParentUsingHighestVersion() throws Exception {

            pluginInPom = findPlugin(plugin, project.getPluginManagement().getPlugins());
        }

        if (pluginInPom != null) {
            if (plugin.getVersion() == null) {
                plugin.setVersion(pluginInPom.getVersion());
            }

            plugin.setDependencies(new ArrayList<>(pluginInPom.getDependencies()));
        }
    }

            if (plugin.getVersion() == null) {
                PluginVersionRequest request = new DefaultPluginVersionRequest(
                        plugin, session.getRepositorySession(), project.getRemotePluginRepositories());
                plugin.setVersion(pluginVersionResolver.resolve(request).getVersion());
            }
            versions.put(plugin.getKey(), plugin.getVersion());
        }

        public ProjectBuilder setArtifactId(String artifactId) {
            project.setArtifactId(artifactId);
            return this;
        }

        public ProjectBuilder setVersion(String version) {
            project.setVersion(version);
            return this;
        }

        // Dependencies
        //

        }
    }

    public void setVersion(String version) {
        getModel().setVersion(version);
    }

    public String getVersion() {
        String version = getModel().getVersion();

        if ((version == null) && (getModel().getParent() != null)) {
            version = getModel().getParent().getVersion();
        }

        return version;
    }

        PluginDescriptor descriptor = new PluginDescriptor();
        descriptor.setGroupId("org.apache.maven.its.plugins");
        descriptor.setArtifactId("maven-it-plugin");
        descriptor.setVersion("0.1");
        List<String> errors = new ArrayList<>();
        mavenPluginValidator.validate(plugin, descriptor, errors);
        assertTrue(errors.isEmpty());
    }

    @Test
    void testInvalidGroupId() {

        extension.setArtifactId(artifactId);
        extension.setVersion(version);
        return extension;
    }

    private static MavenProject createProject(String groupId, String artifactId, String version) {
        Model model = new Model();
        model.setGroupId(groupId);
        model.setArtifactId(artifactId);
        model.setVersion(version);
        model.setBuild(new Build());

        /*
        Dependency dep1 = new Dependency();
        dep1.setGroupId( "test" );
        dep1.setArtifactId( "test-artifact" );
        dep1.setVersion( "1" );
        dep1.setType( "jar" );

        Exclusion exc = new Exclusion();
        exc.setGroupId( "test" );
        exc.setArtifactId( "test-artifact3" );

        dep1.addExclusion( exc );

        pd.setArtifactId("my-plugin");
        pd.setGroupId("org.myco.plugins");
        pd.setVersion("1");

        DefaultArtifact artifact = new DefaultArtifact(
                pd.getGroupId(),
                pd.getArtifactId(),
                pd.getVersion(),
                "compile",
                "maven-plugin",
                "",

        assertEquals(expected, actual);
    }

    @Test
    void testEscapedVariablePassthrough() throws Exception {
        String var = "${var}";

        Model model = new Model();
        model.setVersion("1");

        MavenProject project = new MavenProject(model);

        ExpressionEvaluator ee = createExpressionEvaluator(project, null, new Properties());

        Object value = ee.evaluate("$" + var);