From 6b68b7ffefdc318c79947bcdb88f3c5374785715 Mon Sep 17 00:00:00 2001
From: "Daniel A. A. Pelsmaeker" <developer@pelsmaeker.net>
Date: Wed, 24 Jul 2024 16:01:26 +0200
Subject: [PATCH] Support run. and test. properties

---
 .../convention/JavaConventionPlugin.kt        | 36 +++++++++++++++++--
 docs/content/conventions/java.md              | 10 ++++--
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/convention-plugin/src/main/kotlin/org/metaborg/convention/JavaConventionPlugin.kt b/convention-plugin/src/main/kotlin/org/metaborg/convention/JavaConventionPlugin.kt
index 3a2729e..ba59ace 100644
--- a/convention-plugin/src/main/kotlin/org/metaborg/convention/JavaConventionPlugin.kt
+++ b/convention-plugin/src/main/kotlin/org/metaborg/convention/JavaConventionPlugin.kt
@@ -2,13 +2,16 @@ package org.metaborg.convention
 
 import org.gradle.api.Plugin
 import org.gradle.api.Project
+import org.gradle.api.plugins.ApplicationPlugin
 import org.gradle.api.plugins.JavaPlugin
 import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.api.tasks.JavaExec
 import org.gradle.api.tasks.compile.JavaCompile
 import org.gradle.api.tasks.javadoc.Javadoc
 import org.gradle.api.tasks.testing.Test
 import org.gradle.external.javadoc.CoreJavadocOptions
 import org.gradle.kotlin.dsl.*
+import org.gradle.process.JavaForkOptions
 
 /**
  * Configures a Gradle project that builds a Java library or application.
@@ -34,7 +37,7 @@ class JavaConventionPlugin: Plugin<Project> {
                 withJavadocJar()
             }
 
-            tasks.withType<JavaCompile> {
+            tasks.withType<JavaCompile>().configureEach {
                 // Use UTF-8 encoding by default
                 options.encoding = "UTF-8"
                 // Warn for unchecked casts
@@ -47,7 +50,7 @@ class JavaConventionPlugin: Plugin<Project> {
                 options.compilerArgs.add("-Xdoclint:none")
             }
 
-            tasks.withType<Javadoc> {
+            tasks.withType<Javadoc>().configureEach {
                 options {
                     this as CoreJavadocOptions
                     // Use UTF-8 encoding by default
@@ -61,6 +64,35 @@ class JavaConventionPlugin: Plugin<Project> {
                     quiet()
                 }
             }
+
+            tasks.named<Test>(JavaPlugin.TEST_TASK_NAME) {
+                addPropertiesWithPrefix("test.", project)
+            }
+        }
+
+        plugins.withType<ApplicationPlugin> {
+            tasks.named<JavaExec>(ApplicationPlugin.TASK_RUN_NAME) {
+                addPropertiesWithPrefix("run.", project)
+            }
+        }
+    }
+
+    /**
+     * Adds all system properties and project properties that have the given [prefix] (case-insensitive)
+     * to the properties of the Java process (without the prefix).
+     *
+     * @param prefix The property prefix to look for.
+     * @param project The Gradle project.
+     */
+    private fun JavaForkOptions.addPropertiesWithPrefix(prefix: String, project: Project) {
+        @Suppress("UNCHECKED_CAST")
+        for ((k, v) in System.getProperties() as Map<String, *>) {
+            if (!k.startsWith(prefix, ignoreCase = true)) continue
+            systemProperty(k.substring(prefix.length), v.toString())
+        }
+        for ((k, v) in project.properties) {
+            if (!k.startsWith(prefix, ignoreCase = true)) continue
+            systemProperty(k.substring(prefix.length), v.toString())
         }
     }
 }
diff --git a/docs/content/conventions/java.md b/docs/content/conventions/java.md
index ee7eea0..e5e0185 100644
--- a/docs/content/conventions/java.md
+++ b/docs/content/conventions/java.md
@@ -2,9 +2,15 @@
 title: "Java Convention"
 ---
 # Java Convention Plugin
-The Java convention plugin configures a project to be built using Java 11 by default, but this can be overridden.
+The Java convention plugin configures a project to:
 
-To use the plugin, you need to apply both the Java convention plugin and one of the Java plugins (`java-library`, `java`):
+- build using a Java 11 toolchain by default;
+- silence JavaDoc warnings and errors as much as possible;
+- use UTF-8 encoding;
+- transfer properties prefixed with `app.` to the `run` task if the Java `application` plugin is applied;
+- transfer properties prefixed with `test.` to the `test` task.
+
+To use the plugin, you need to apply both the Java convention plugin and one of the Java plugins (e.g., `java-library`, `java`):
 
 ```kotlin title="build.gradle.kts"
 plugins {