clean output directory before first test case is processed

allure-java-commons/build.gradle.kts

@@ -6,6 +6,7 @@ description = "Allure Java Commons"
 
 dependencies {
     api("org.slf4j:slf4j-api")
+    api("commons-io:commons-io")
     api(project(":allure-model"))
     compileOnly("org.aspectj:aspectjrt")
     internal("com.fasterxml.jackson.core:jackson-databind")

allure-java-commons/src/main/java/io/qameta/allure/FileSystemResultsWriter.java

@@ -19,13 +19,15 @@
 import io.qameta.allure.internal.Allure2ModelJackson;
 import io.qameta.allure.model.TestResult;
 import io.qameta.allure.model.TestResultContainer;
+import org.apache.commons.io.FileUtils;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Objects;
 import java.util.UUID;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  * @author charlie (Dmitry Baev).
@@ -36,6 +38,8 @@ public class FileSystemResultsWriter implements AllureResultsWriter {
 
     private final ObjectMapper mapper;
 
+    private final AtomicBoolean isOutputCleaned = new AtomicBoolean(false);
+
     public FileSystemResultsWriter(final Path outputDirectory) {
         this.outputDirectory = outputDirectory;
         this.mapper = Allure2ModelJackson.createMapper();
@@ -46,6 +50,7 @@ public void write(final TestResult testResult) {
         final String testResultName = Objects.isNull(testResult.getUuid())
                 ? generateTestResultName()
                 : generateTestResultName(testResult.getUuid());
+        cleanDirectoriesIfNeeded(outputDirectory);
         createDirectories(outputDirectory);
         final Path file = outputDirectory.resolve(testResultName);
         try {
@@ -60,6 +65,7 @@ public void write(final TestResultContainer testResultContainer) {
         final String testResultContainerName = Objects.isNull(testResultContainer.getUuid())
                 ? generateTestResultContainerName()
                 : generateTestResultContainerName(testResultContainer.getUuid());
+        cleanDirectoriesIfNeeded(outputDirectory);
         createDirectories(outputDirectory);
         final Path file = outputDirectory.resolve(testResultContainerName);
         try {
@@ -71,6 +77,7 @@ public void write(final TestResultContainer testResultContainer) {
 
     @Override
     public void write(final String source, final InputStream attachment) {
+        cleanDirectoriesIfNeeded(outputDirectory);
         createDirectories(outputDirectory);
         final Path file = outputDirectory.resolve(source);
         try (InputStream is = attachment) {
@@ -80,6 +87,17 @@ public void write(final String source, final InputStream attachment) {
         }
     }
 
+    private void cleanDirectoriesIfNeeded(final Path directory) {
+        if (isOutputCleaned.compareAndSet(false, true)) {
+            try {
+                FileUtils.deleteDirectory(directory.toFile());
+            } catch (IOException e) {
+                throw new AllureResultsWriteException("Could not clean Allure results directory", e);
+            }
+        }
+
+    }
+
     private void createDirectories(final Path directory) {
         try {
             Files.createDirectories(directory);

allure-java-commons/src/test/java/io/qameta/allure/FileSystemResultsWriterTest.java

@@ -19,6 +19,8 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
+import java.io.File;
+import java.io.IOException;
 import java.nio.file.Path;
 import java.util.UUID;
 
@@ -53,4 +55,25 @@ void shouldWriteTestResult(@TempDir final Path folder) {
         assertThat(folder.resolve(fileName))
                 .isRegularFile();
     }
+
+    @Test
+    void shouldCleanResultsDirectoryBeforeFirstTestResult(@TempDir final Path folder) throws IOException {
+        final String existingFileName = "existing-file.json";
+        final File existingFile = new File(folder.toFile(), existingFileName);
+        existingFile.createNewFile();
+
+        assertThat(folder).isDirectory();
+        assertThat(folder.resolve(existingFile.getName())).isRegularFile();
+
+        FileSystemResultsWriter writer = new FileSystemResultsWriter(folder);
+        final String uuid = UUID.randomUUID().toString();
+        final TestResult testResult = current().nextObject(TestResult.class, "steps").setUuid(uuid);
+        writer.write(testResult);
+
+        final String fileName = generateTestResultName(uuid);
+        assertThat(folder).isDirectory();
+        assertThat(folder.resolve(fileName)).isRegularFile();
+        assertThat(folder.resolve(existingFileName)).doesNotExist();
+    }
+
 }