Adjust Enigma Directory detection to require at least one contained .mapping file

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Made `OuterClassNamePropagator` configurable
 - Made Enigma writer always output destination names if visited explicitly, establishing consistency across all writers
 - Added a simplified `MappingNsCompleter` constructor for completing all destination names with the source names
+- Adjusted format detection to only return ENIGMA_DIR for non-empty directories with at least one `.mapping` file
 
 ## [0.7.1] - 2025-01-07
 - Restored the ability to read source-namespace-only mapping files, even if not spec-compliant

src/main/java/net/fabricmc/mappingio/MappingReader.java

@@ -21,10 +21,14 @@
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.jetbrains.annotations.Nullable;
 
@@ -46,13 +50,28 @@ private MappingReader() {
 	}
 
 	@Nullable
-	public static MappingFormat detectFormat(Path file) throws IOException {
-		if (Files.isDirectory(file)) {
-			return MappingFormat.ENIGMA_DIR;
+	public static MappingFormat detectFormat(Path path) throws IOException {
+		if (Files.isDirectory(path)) {
+			String enigmaExt = "." + MappingFormat.ENIGMA_FILE.fileExt;
+			AtomicReference<MappingFormat> ret = new AtomicReference<>();
+
+			Files.walkFileTree(path, new SimpleFileVisitor<Path>() {
+				@Override
+				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+					if (file.getFileName().toString().endsWith(enigmaExt)) {
+						ret.set(MappingFormat.ENIGMA_DIR);
+						return FileVisitResult.TERMINATE;
+					}
+
+					return FileVisitResult.CONTINUE;
+				}
+			});
+
+			return ret.get();
 		}
 
-		try (Reader reader = new InputStreamReader(Files.newInputStream(file), StandardCharsets.UTF_8)) {
-			String fileName = file.getFileName().toString();
+		try (Reader reader = new InputStreamReader(Files.newInputStream(path), StandardCharsets.UTF_8)) {
+			String fileName = path.getFileName().toString();
 			int dotIdx = fileName.lastIndexOf('.');
 			String fileExt = dotIdx >= 0 ? fileName.substring(dotIdx + 1) : null;
 

src/test/java/net/fabricmc/mappingio/test/tests/reading/DetectionTest.java

@@ -17,6 +17,7 @@
 package net.fabricmc.mappingio.test.tests.reading;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.InputStreamReader;
@@ -35,21 +36,28 @@
 import net.fabricmc.mappingio.test.visitors.NopMappingVisitor;
 
 public class DetectionTest {
-	private static final MappingDir dir = TestMappings.DETECTION;
-
 	@Test
 	public void run() throws Exception {
-		for (MappingFormat format : MappingFormat.values()) {
-			if (format == MappingFormat.RECAF_SIMPLE_FILE) {
-				assertThrows(AssertionFailedError.class, () -> check(format));
-			} else {
-				check(format);
+		for (MappingDir dir : TestMappings.values()) {
+			for (MappingFormat format : MappingFormat.values()) {
+				if (format == MappingFormat.RECAF_SIMPLE_FILE) {
+					assertThrows(AssertionFailedError.class, () -> check(dir, format));
+				} else {
+					check(dir, format);
+				}
 			}
 		}
+
+		assertNull(MappingReader.detectFormat(TestMappings.DETECTION.path().resolve("non-mapping-dir")));
 	}
 
-	private void check(MappingFormat format) throws Exception {
+	private void check(MappingDir dir, MappingFormat format) throws Exception {
 		Path path = dir.pathFor(format);
+
+		if (!Files.exists(path)) {
+			return;
+		}
+
 		assertEquals(format, MappingReader.detectFormat(path));
 
 		if (!format.hasSingleFile()) return;

src/test/resources/detection/non-mapping-dir/text.txt

@@ -0,0 +1 @@
+test