Add system-indepentant FileTypeDetector for tests

src/test/java/org/perfectable/repositable/AbstractServerTest.java

@@ -33,7 +33,7 @@ public abstract class AbstractServerTest {
 
 	private static final MediaType METADATA_MEDIA_TYPE = MediaType.XML_UTF_8;
 	private static final MediaType HASH_MEDIA_TYPE = MediaType.create("text", "plain");
-	private static final MediaType SIGNATURE_MEDIA_TYPE = MediaType.create("text", "plain");
+	private static final MediaType SIGNATURE_MEDIA_TYPE = MediaType.create("application", "pgp-signature");
 
 	private static final String UPLOAD_METHOD = "PUT";
 

src/test/java/org/perfectable/repositable/ExtensionOnlyFileTypeDetector.java

@@ -0,0 +1,26 @@
+package org.perfectable.repositable;
+
+import java.nio.file.Path;
+import java.nio.file.spi.FileTypeDetector;
+
+import com.google.common.collect.ImmutableMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ExtensionOnlyFileTypeDetector extends FileTypeDetector {
+	private static final ImmutableMap<String, String> REGISTERED_EXTENSIONS = ImmutableMap.<String, String>builder()
+		.put("jar", "application/java-archive")
+		.put("asc", "application/pgp-signature")
+		.build();
+
+	@SuppressWarnings("override.return.invalid")
+	@Override
+	public @Nullable String probeContentType(Path path) {
+		String fileName = path.getFileName().toString();
+		int extensionSeparator = fileName.lastIndexOf(".");
+		if (extensionSeparator < 0) {
+			return null;
+		}
+		String extension = fileName.substring(extensionSeparator + 1);
+		return REGISTERED_EXTENSIONS.get(extension);
+	}
+}

src/test/resources/META-INF/services/java.nio.file.spi.FileTypeDetector

@@ -0,0 +1 @@
+org.perfectable.repositable.ExtensionOnlyFileTypeDetector