Give FileLocator an in-place locator capability.

plugin-maven/src/main/java/com/diffplug/spotless/maven/FileLocator.java

@@ -21,6 +21,8 @@
 import java.util.Objects;
 import java.util.UUID;
 
+import javax.annotation.Nullable;
+
 import org.codehaus.plexus.resource.ResourceManager;
 import org.codehaus.plexus.resource.loader.FileResourceCreationException;
 import org.codehaus.plexus.resource.loader.ResourceNotFoundException;
@@ -38,7 +40,11 @@ public FileLocator(ResourceManager resourceManager, File buildDir) {
 		this.buildDir = Objects.requireNonNull(buildDir);
 	}
 
-	public File locateFile(String path) {
+	/**
+	 * Resolves the given file (not folder) from the project directory, but does so by copying it to a random
+	 * filename with the same extension in the build directory.
+	 */
+	public @Nullable File locateFile(@Nullable String path) {
 		if (isNullOrEmpty(path)) {
 			return null;
 		}
@@ -58,7 +64,14 @@ private static String tmpOutputFileName(String path) {
 		return TMP_RESOURCE_FILE_PREFIX + UUID.randomUUID() + '.' + extension;
 	}
 
-	public File getBuildDir() {
-		return this.buildDir;
+	/**
+	 * Resolves the given file or folder from the project directory, doesn't have to exist.
+	 */
+	public File resolve(String path) {
+		if (path.isEmpty() || path.equals(".")) {
+			return buildDir;
+		} else {
+			return new File(buildDir, path);
+		}
 	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/typescript/Tsfmt.java

@@ -15,8 +15,6 @@
  */
 package com.diffplug.spotless.maven.typescript;
 
-import static com.diffplug.common.base.Strings.isNullOrEmpty;
-
 import java.io.File;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -59,22 +57,8 @@ public class Tsfmt implements FormatterStepFactory {
 	@Parameter
 	private Map<String, String> config;
 
-	private File locateFile(String path) {
-		if (isNullOrEmpty(path)) {
-			return null;
-		}
-
-		File exists = new File(path);
-		if (exists.exists()) {
-			return exists;
-		}
-
-		throw new RuntimeException("Unable to locate file with path: " + path);
-	}
-
 	@Override
 	public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
-
 		Map<String, String> devDependencies = TsFmtFormatterStep.defaultDevDependencies();
 		if (typescriptFormatterVersion != null) {
 			devDependencies.put("typescript-formatter", typescriptFormatterVersion);
@@ -100,13 +84,13 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 			}
 			configInline = null;
 			if (this.tsconfigFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSCONFIG, locateFile(tsconfigFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSCONFIG, stepConfig.getFileLocator().resolve(tsconfigFile));
 			} else if (this.tsfmtFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSFMT, locateFile(tsfmtFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSFMT, stepConfig.getFileLocator().resolve(tsfmtFile));
 			} else if (this.tslintFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSLINT, locateFile(tslintFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.TSLINT, stepConfig.getFileLocator().resolve(tslintFile));
 			} else if (this.vscodeFile != null) {
-				configFile = new TypedTsFmtConfigFile(TsConfigFileType.VSCODE, locateFile(vscodeFile));
+				configFile = new TypedTsFmtConfigFile(TsConfigFileType.VSCODE, stepConfig.getFileLocator().resolve(vscodeFile));
 			} else {
 				throw new Error("Programming error: the xors did not match the cases");
 			}
@@ -129,7 +113,7 @@ public FormatterStep newFormatterStep(FormatterStepConfig stepConfig) {
 			throw onlyOneConfig();
 		}
 
-		File buildDir = stepConfig.getFileLocator().getBuildDir();
+		File buildDir = stepConfig.getFileLocator().resolve(".");
 		return TsFmtFormatterStep.create(devDependencies, stepConfig.getProvisioner(), buildDir, npm, configFile, configInline);
 	}