From 7c485f5c3df13cbc4e8455011a39050b9cf462aa Mon Sep 17 00:00:00 2001
From: Artur Bosch <abosch@posteo.de>
Date: Thu, 9 Jun 2022 00:34:47 +0200
Subject: [PATCH] Provide a priority field for DetektProvider so tools can
 easier choose their provider implemention in tests for example (#4923)

---
 detekt-tooling/api/detekt-tooling.api         |  5 +++++
 .../detekt/tooling/api/DetektProvider.kt      | 11 +++++++++-
 .../detekt/tooling/api/DetektProviderSpec.kt  | 20 +++++++++++++++++++
 ...o.github.detekt.tooling.api.DetektProvider |  1 +
 4 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 detekt-tooling/src/test/kotlin/io/github/detekt/tooling/api/DetektProviderSpec.kt
 create mode 100644 detekt-tooling/src/test/resources/META-INF/services/io.github.detekt.tooling.api.DetektProvider

diff --git a/detekt-tooling/api/detekt-tooling.api b/detekt-tooling/api/detekt-tooling.api
index 8cd9687dfbd..942a05e44b7 100644
--- a/detekt-tooling/api/detekt-tooling.api
+++ b/detekt-tooling/api/detekt-tooling.api
@@ -45,6 +45,7 @@ public abstract class io/github/detekt/tooling/api/DetektError : java/lang/Runti
 public abstract interface class io/github/detekt/tooling/api/DetektProvider {
 	public static final field Companion Lio/github/detekt/tooling/api/DetektProvider$Companion;
 	public abstract fun get (Lio/github/detekt/tooling/api/spec/ProcessingSpec;)Lio/github/detekt/tooling/api/Detekt;
+	public abstract fun getPriority ()I
 }
 
 public final class io/github/detekt/tooling/api/DetektProvider$Companion {
@@ -52,6 +53,10 @@ public final class io/github/detekt/tooling/api/DetektProvider$Companion {
 	public static synthetic fun load$default (Lio/github/detekt/tooling/api/DetektProvider$Companion;Ljava/lang/ClassLoader;ILjava/lang/Object;)Lio/github/detekt/tooling/api/DetektProvider;
 }
 
+public final class io/github/detekt/tooling/api/DetektProvider$DefaultImpls {
+	public static fun getPriority (Lio/github/detekt/tooling/api/DetektProvider;)I
+}
+
 public abstract class io/github/detekt/tooling/api/FunctionMatcher {
 	public static final field Companion Lio/github/detekt/tooling/api/FunctionMatcher$Companion;
 	public abstract fun match (Lorg/jetbrains/kotlin/descriptors/CallableDescriptor;)Z
diff --git a/detekt-tooling/src/main/kotlin/io/github/detekt/tooling/api/DetektProvider.kt b/detekt-tooling/src/main/kotlin/io/github/detekt/tooling/api/DetektProvider.kt
index 6dce9d63373..3100b9a8b50 100644
--- a/detekt-tooling/src/main/kotlin/io/github/detekt/tooling/api/DetektProvider.kt
+++ b/detekt-tooling/src/main/kotlin/io/github/detekt/tooling/api/DetektProvider.kt
@@ -8,6 +8,13 @@ import java.util.ServiceLoader
  */
 interface DetektProvider {
 
+    /**
+     * Is used to choose the highest priority provider if more than one are found on the classpath.
+     *
+     * Can be useful to stub/mock detekt instances for tests.
+     */
+    val priority: Int get() = -1
+
     /**
      * Configure a [Detekt] instance based on given [ProcessingSpec].
      */
@@ -21,6 +28,8 @@ interface DetektProvider {
         fun load(
             classLoader: ClassLoader = DetektProvider::class.java.classLoader
         ): DetektProvider =
-            ServiceLoader.load(DetektProvider::class.java, classLoader).first()
+            ServiceLoader.load(DetektProvider::class.java, classLoader)
+                .maxByOrNull { it.priority }
+                ?: error("No implemention of DetektProvider found.")
     }
 }
diff --git a/detekt-tooling/src/test/kotlin/io/github/detekt/tooling/api/DetektProviderSpec.kt b/detekt-tooling/src/test/kotlin/io/github/detekt/tooling/api/DetektProviderSpec.kt
new file mode 100644
index 00000000000..1cc0bebaa62
--- /dev/null
+++ b/detekt-tooling/src/test/kotlin/io/github/detekt/tooling/api/DetektProviderSpec.kt
@@ -0,0 +1,20 @@
+package io.github.detekt.tooling.api
+
+import io.github.detekt.tooling.api.spec.ProcessingSpec
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class DetektProviderSpec {
+
+    @Test
+    fun `load provider with highest priority`() {
+        val provider = DetektProvider.load()
+
+        assertThat(provider.priority).isEqualTo(100)
+    }
+}
+
+class PrioritizedProvider : DetektProvider {
+    override val priority: Int = 100
+    override fun get(processingSpec: ProcessingSpec): Detekt = error("No instances.")
+}
diff --git a/detekt-tooling/src/test/resources/META-INF/services/io.github.detekt.tooling.api.DetektProvider b/detekt-tooling/src/test/resources/META-INF/services/io.github.detekt.tooling.api.DetektProvider
new file mode 100644
index 00000000000..6901985c943
--- /dev/null
+++ b/detekt-tooling/src/test/resources/META-INF/services/io.github.detekt.tooling.api.DetektProvider
@@ -0,0 +1 @@
+io.github.detekt.tooling.api.PrioritizedProvider