wait until java plugin applied (#6)

changelog/@unreleased/pr-6.v2.yml

@@ -0,0 +1,5 @@
+type: fix
+fix:
+  description: wait until java plugin applied
+  links:
+  - https://github.com/palantir/gradle-plugin-testing/pull/6

gradle-plugin-testing/src/main/java/com/palantir/gradle/plugintesting/PluginTestingPlugin.java

@@ -41,8 +41,15 @@ public class PluginTestingPlugin implements Plugin<Project> {
      */
     @Override
     public void apply(Project project) {
-        PluginTestingExtension testUtilsExt =
-                project.getExtensions().create(PluginTestingExtension.EXTENSION_NAME, PluginTestingExtension.class);
+        project.getExtensions().create(PluginTestingExtension.EXTENSION_NAME, PluginTestingExtension.class);
+        // need the SourceSetContainer extension so need to wait until java plugin is applied
+        project.getPluginManager().withPlugin("java", _unused -> {
+            doApply(project);
+        });
+    }
+
+    private static void doApply(Project project) {
+        PluginTestingExtension testUtilsExt = project.getExtensions().getByType(PluginTestingExtension.class);
 
         addTestDependency(project);
 

gradle-plugin-testing/src/test/groovy/com/palantir/gradle/plugintesting/PluginTestingPluginIntegrationSpec.groovy

@@ -143,6 +143,19 @@ class PluginTestingPluginIntegrationSpec extends IntegrationSpec {
         !result.success
     }
 
+    def 'works when applied before other plugins'() {
+        given:
+        buildFile.text = """
+            apply plugin: 'com.palantir.gradle-plugin-testing'
+        """.stripIndent(true) + buildFile.text
+
+        when:
+        def result = runTasks('test')
+
+        then:
+        result.success
+    }
+
     def 'resolve dependencies'() {
         given:
         applyTestUtilsPlugin()