Check if ktlint_code_style is set in .editorconfig before overriding it

ktlint_code_style gets unconditionally overridden to its default value
(intellij_idea) when the editorConfigOverride map is non-empty but does
not define it. As a result, it gets overridden even if it's actually
defined in the .editorconfig file.

This change checks if ktlint_code_style is already defined in
.editorconfig before overriding it to its default value.

Fixes #2142.

Author: OlivierGenez

lib/src/compatKtLint1Dot0Dot0/java/com/diffplug/spotless/glue/ktlint/compat/KtLintCompat1Dot0Dot0Adapter.java

@@ -93,20 +93,21 @@ public String format(
 				.flatMap(loader -> loader.get().getRuleProviders().stream())
 				.collect(Collectors.toUnmodifiableSet());
 
-		EditorConfigOverride editorConfigOverride;
-		if (editorConfigOverrideMap.isEmpty()) {
-			editorConfigOverride = EditorConfigOverride.Companion.getEMPTY_EDITOR_CONFIG_OVERRIDE();
-		} else {
-			editorConfigOverride = createEditorConfigOverride(allRuleProviders.stream().map(
-					RuleProvider::createNewRuleInstance).collect(Collectors.toList()),
-					editorConfigOverrideMap);
-		}
 		EditorConfigDefaults editorConfig;
 		if (editorConfigPath == null || !Files.exists(editorConfigPath)) {
 			editorConfig = EditorConfigDefaults.Companion.getEMPTY_EDITOR_CONFIG_DEFAULTS();
 		} else {
 			editorConfig = EditorConfigDefaults.Companion.load(editorConfigPath, RuleProviderKt.propertyTypes(allRuleProviders));
 		}
+		EditorConfigOverride editorConfigOverride;
+		if (editorConfigOverrideMap.isEmpty()) {
+			editorConfigOverride = EditorConfigOverride.Companion.getEMPTY_EDITOR_CONFIG_OVERRIDE();
+		} else {
+			editorConfigOverride = createEditorConfigOverride(
+					editorConfig,
+					allRuleProviders.stream().map(RuleProvider::createNewRuleInstance).collect(Collectors.toList()),
+					editorConfigOverrideMap);
+		}
 
 		return new KtLintRuleEngine(
 				allRuleProviders,
@@ -120,7 +121,7 @@ public String format(
 	/**
 	 * Create EditorConfigOverride from user provided parameters.
 	 */
-	private static EditorConfigOverride createEditorConfigOverride(final List<Rule> rules, Map<String, Object> editorConfigOverrideMap) {
+	private static EditorConfigOverride createEditorConfigOverride(final EditorConfigDefaults editorConfig, final List<Rule> rules, Map<String, Object> editorConfigOverrideMap) {
 		// Get properties from rules in the rule sets
 		Stream<EditorConfigProperty<?>> ruleProperties = rules.stream()
 				.flatMap(rule -> rule.getUsesEditorConfigProperties().stream());
@@ -132,7 +133,9 @@ private static EditorConfigOverride createEditorConfigOverride(final List<Rule>
 				.collect(Collectors.toMap(EditorConfigProperty::getName, property -> property));
 
 		// The default style had been changed from intellij_idea to ktlint_official in version 1.0.0
-		if (!editorConfigOverrideMap.containsKey("ktlint_code_style")) {
+		boolean isCodeStyleDefinedInEditorConfig = editorConfig.getValue().getSections().stream()
+				.anyMatch(section -> section.getProperties().containsKey("ktlint_code_style"));
+		if (!isCodeStyleDefinedInEditorConfig && !editorConfigOverrideMap.containsKey("ktlint_code_style")) {
 			editorConfigOverrideMap.put("ktlint_code_style", "intellij_idea");
 		}
 

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/KotlinExtensionTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 DiffPlug
+ * Copyright 2016-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -127,6 +127,25 @@ void testReadCodeStyleFromEditorConfigFile() throws IOException {
 		checkKtlintOfficialStyle();
 	}
 
+	@Test
+	void testEditorConfigOverrideWithUnsetCodeStyleDoesNotOverrideEditorConfigCodeStyleWithDefault() throws IOException {
+		setFile(".editorconfig").toResource("kotlin/ktlint/ktlint_official/.editorconfig");
+		setFile("build.gradle").toLines(
+				"plugins {",
+				"    id 'org.jetbrains.kotlin.jvm' version '1.6.21'",
+				"    id 'com.diffplug.spotless'",
+				"}",
+				"repositories { mavenCentral() }",
+				"spotless {",
+				"    kotlin {",
+				"        ktlint().editorConfigOverride([",
+				"	         ktlint_test_key: true,",
+				"        ])",
+				"    }",
+				"}");
+		checkKtlintOfficialStyle();
+	}
+
 	@Test
 	void testSetEditorConfigCanOverrideEditorConfigFile() throws IOException {
 		setFile(".editorconfig").toResource("kotlin/ktlint/intellij_idea/.editorconfig");