support built-in gradle plugins in testkit DSL

Author: John Burns

src/main/java/nebula/test/dsl/Plugin.java

@@ -0,0 +1,69 @@
+package nebula.test.dsl;
+
+import org.jspecify.annotations.Nullable;
+
+public class Plugin {
+    @Nullable
+    private String builtIn;
+    @Nullable
+    private String builtInParam;
+    private final String id;
+    @Nullable
+    private String version;
+
+    Plugin(String id) {
+        this.id = id;
+    }
+
+    /**
+     * Set the version of the plugin.
+     * This only needs to be called for plugins not already on the classpath
+     *
+     * @param version the version of the plugin
+     */
+    @NebulaTestKitDsl
+    public void version(String version) {
+        this.version = version;
+    }
+
+    public Plugin builtIn(String builtInName) {
+        builtIn = builtInName;
+        return this;
+    }
+
+    public Plugin builtInParam(String builtInParamName) {
+        builtInParam = builtInParamName;
+        return this;
+    }
+
+    public String render(BuildscriptLanguage language) {
+        final StringBuilder stringBuilder = new StringBuilder();
+
+        if (language == BuildscriptLanguage.GROOVY) {
+            stringBuilder.append("id '").append(id).append("'");
+        } else if (language == BuildscriptLanguage.KOTLIN) {
+            if (builtIn != null) {
+                if (builtInParam == null) {
+                    if (builtIn.contains("-")) {
+                        stringBuilder.append("`").append(builtIn).append("`");
+                    } else {
+                        stringBuilder.append(builtIn);
+                    }
+                } else {
+                    stringBuilder.append(builtIn).append("(\"").append(builtInParam).append("\")");
+                }
+            } else {
+                stringBuilder.append("id(\"").append(id).append("\")");
+            }
+        }
+
+        if (version != null) {
+            if (language == BuildscriptLanguage.GROOVY) {
+                stringBuilder.append(" version '").append(version).append("'");
+            } else if (language == BuildscriptLanguage.KOTLIN) {
+                stringBuilder.append(" version (\"").append(version).append("\")");
+            }
+        }
+        return stringBuilder.toString();
+    }
+}

src/main/java/nebula/test/dsl/PluginsBuilder.java

@@ -1,7 +1,6 @@
 package nebula.test.dsl;
 
 import org.jspecify.annotations.NullMarked;
-import org.jspecify.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -30,7 +29,23 @@ public Plugin id(String id) {
      */
     @NebulaTestKitDsl
     public void java() {
-        plugins.add(new Plugin("java"));
+        id("java").builtIn("java");
+    }
+
+    /**
+     * Adds a kotlin plugin
+     */
+    @NebulaTestKitDsl
+    public Plugin kotlin(String platform) {
+        return id("org.jetbrains.kotlin." + platform).builtIn("kotlin").builtInParam(platform);
+    }
+
+    /**
+     * Adds kotlin-dsl plugin
+     */
+    @NebulaTestKitDsl
+    public Plugin kotlinDsl() {
+        return id("org.gradle.kotlin.kotlin-dsl").builtIn("kotlin-dsl");
     }
 
     boolean hasContent() {
@@ -48,44 +63,4 @@ String build(BuildscriptLanguage language, int indentation) {
         }
         return stringBuilder.toString();
     }
-
-    // TODO support "built-in" plugins like java similar to the repository builtins like mavenCentral()
-    public static class Plugin {
-        private final String id;
-        @Nullable
-        private String version;
-
-        Plugin(String id) {
-            this.id = id;
-        }
-
-        /**
-         * Set the version of the plugin.
-         * This only needs to be called for plugins not already on the classpath
-         *
-         * @param version the version of the plugin
-         */
-        @NebulaTestKitDsl
-        public void version(String version) {
-            this.version = version;
-        }
-
-        String render(BuildscriptLanguage language) {
-            final StringBuilder stringBuilder = new StringBuilder();
-            if (language == BuildscriptLanguage.GROOVY) {
-                stringBuilder.append("id '").append(id).append("'");
-            } else if (language == BuildscriptLanguage.KOTLIN) {
-                stringBuilder.append("id(\"").append(id).append("\")");
-            }
-
-            if (version != null) {
-                if (language == BuildscriptLanguage.GROOVY) {
-                    stringBuilder.append(" version '").append(version).append("'");
-                } else if (language == BuildscriptLanguage.KOTLIN) {
-                    stringBuilder.append(" version (\"").append(version).append("\")");
-                }
-            }
-            return stringBuilder.toString();
-        }
-    }
 }

src/main/kotlin/nebula/test/dsl/KotlinDsl.kt

@@ -54,7 +54,7 @@ fun ProjectBuilder.repositories(config: RepositoriesBuilder.() -> Unit) {
 }
 
 @NebulaTestKitDsl
-infix fun PluginsBuilder.Plugin.version(version: String) {
+infix fun Plugin.version(version: String) {
     version(version)
 }
 

src/test/java/nebula/test/dsl/PluginsBuilderTest.java

@@ -55,7 +55,7 @@ public void testKotlinJava(){
         //language=groovy
         assertThat(actual).isEqualTo("""
                 plugins {
-                    id("java")
+                    java
                 }
                 """);
     }
@@ -72,4 +72,58 @@ public void testKotlinIdWithVersion(){
                 }
                 """);
     }
+
+    @Test
+    public void testKotlinJvm_kotlin(){
+        final var builder = new PluginsBuilder();
+        builder.kotlin("jvm").version("0.0.0");
+        final var actual = builder.build(BuildscriptLanguage.KOTLIN,0);
+        //language=kotlin
+        assertThat(actual).isEqualTo("""
+                plugins {
+                    kotlin("jvm") version ("0.0.0")
+                }
+                """);
+    }
+
+
+    @Test
+    public void testKotlinJvm_groovy(){
+        final var builder = new PluginsBuilder();
+        builder.kotlin("jvm").version("0.0.0");
+        final var actual = builder.build(BuildscriptLanguage.GROOVY,0);
+        //language=groovy
+        assertThat(actual).isEqualTo("""
+                plugins {
+                    id 'org.jetbrains.kotlin.jvm' version '0.0.0'
+                }
+                """);
+    }
+
+    @Test
+    public void testKotlinDsl_kotlin(){
+        final var builder = new PluginsBuilder();
+        builder.kotlinDsl();
+        final var actual = builder.build(BuildscriptLanguage.KOTLIN,0);
+        //language=kotlin
+        assertThat(actual).isEqualTo("""
+                plugins {
+                    `kotlin-dsl`
+                }
+                """);
+    }
+
+    @Test
+    public void testKotlinDsl_groovy(){
+        final var builder = new PluginsBuilder();
+        builder.kotlinDsl().version("0.0.0");
+        final var actual = builder.build(BuildscriptLanguage.GROOVY,0);
+        //language=groovy
+        assertThat(actual).isEqualTo("""
+                plugins {
+                    id 'org.gradle.kotlin.kotlin-dsl' version '0.0.0'
+                }
+                """);
+    }
+
 }

src/test/java/nebula/test/dsl/ProjectBuilderTest.java

@@ -17,7 +17,7 @@ public void testJavaPlugin(@TempDir File testProjectDir) {
         assertThat(testProjectDir.toPath().resolve("build.gradle.kts")).content()
                 .contains("""
                         plugins {
-                            id("java")
+                            java
                         }""");
     }