feat: allow specifying idea execs not on path

Author: simschla

.gitignore

@@ -7,6 +7,7 @@
 # Project-specific stuff
 userHome/
 workspace/
+testenv.properties
 
 ### Gradle ###
 .gradle

gradle/special-tests.gradle

@@ -38,5 +38,9 @@ tasks.named('test').configure {
 special.forEach { tag ->
 	tasks.register("test${tag.capitalize()}", Test) {
 		useJUnitPlatform { includeTags tag }
+		if (rootProject.file('testenv.properties').exists()) {
+			systemProperty 'testenv.properties.path', rootProject.file('testenv.properties').canonicalPath
+		}
 	}
 }
+

lib/src/main/java/com/diffplug/spotless/generic/IdeaStep.java

@@ -161,17 +161,22 @@ private static String resolveFullBinaryPathAndCheckVersion(String binaryPath) {
 
 		@CheckForNull
 		private static String pathToExe(String binaryPath) {
-			return macOsFix(binaryPath);
+			String testEnvBinaryPath = TestEnvVars.read().get(String.format("%s.%s", IdeaStep.class.getName(), "binaryPath"));
+			if (testEnvBinaryPath != null) {
+				return testEnvBinaryPath;
+			}
+			if (isMacOs()) {
+				return macOsFix(binaryPath);
+			}
+			if (new File(binaryPath).exists()) {
+				return binaryPath;
+			}
+			return null; // search in PATH
 		}
 
 		@CheckForNull
 		private static String macOsFix(String binaryPath) {
-			if (!isMacOs()) {
-				if (new File(binaryPath).exists()) {
-					return binaryPath;
-				}
-				return null; // search in PATH
-			}
+
 			// on macOS, the binary is located in the .app bundle which might be invisible to the user
 			// we try need to append the path to the binary
 			File binary = new File(binaryPath);

lib/src/main/java/com/diffplug/spotless/generic/TestEnvVars.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2025 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.generic;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import javax.annotation.Nullable;
+
+class TestEnvVars {
+
+	private final Map<String, String> envVars;
+
+	private static TestEnvVars INSTANCE;
+
+	private TestEnvVars(Map<String, String> envVars) {
+		this.envVars = Map.copyOf(envVars);
+	}
+
+	public static synchronized TestEnvVars read() {
+		if (INSTANCE == null) {
+			INSTANCE = new TestEnvVars(readTestEnvVars());
+		}
+		return INSTANCE;
+	}
+
+	private static Map<String, String> readTestEnvVars() {
+		Map<String, String> envVars = new HashMap<>();
+		Optional<Path> resolvedTestenvProps = candidateTestEnvLocations().filter(Files::exists).findFirst();
+		resolvedTestenvProps.ifPresent(testenvProps -> {
+			try (var reader = Files.newBufferedReader(testenvProps)) {
+				java.util.Properties properties = new java.util.Properties();
+				properties.load(reader);
+				for (String name : properties.stringPropertyNames()) {
+					envVars.put(name, properties.getProperty(name));
+				}
+			} catch (IOException e) {
+				throw new RuntimeException("Failed to read test environment variables", e);
+			}
+		});
+		return envVars;
+	}
+
+	private static Stream<Path> candidateTestEnvLocations() {
+		Stream.Builder<Path> builder = Stream.builder();
+		if (System.getProperty("testenv.properties.path") != null) {
+			builder.add(Path.of(System.getProperty("testenv.properties.path")));
+		}
+		builder.add(
+				Path.of(System.getProperty("user.dir"), "testenv.properties"));
+		builder.add(
+				Path.of(System.getProperty("user.dir")).getParent().resolve("testenv.properties"));
+		return builder.build();
+	}
+
+	public @Nullable String get(String key) {
+		return envVars.get(key);
+	}
+
+	public String getOrDefault(String key, String defaultValue) {
+		return envVars.getOrDefault(key, defaultValue);
+	}
+
+	public String getOrThrow(String key) {
+		String value = envVars.get(key);
+		if (value == null) {
+			throw new IllegalArgumentException("Environment variable " + key + " not found");
+		}
+		return value;
+	}
+
+	public boolean hasKey(String key) {
+		return envVars.containsKey(key);
+	}
+}