[junitlauncher] - Switch back to issuing a separate LauncherDiscoveryRequest

for each of the test class that are selected by the <testclasses> usage

In 1.10.5 version (the latest released) of Ant, we used to launch
multiple LauncherDiscoveryRequest (a JUnit 5 construct), one each
for a test class, that belonged to the <testclasses> usage. Commit
3f806148c3 changed it to launch one
single LauncherDiscoveryRequest (and including all those test
classes in that request) because it seemed more logical to do so.
However, recent tests/experimentation of the master branch has
shown that it introduces complexities when the "legacy-xml"
listener (the one which supports generating test results in xml
format that junitreport understands) is used. These complexities
include - expecting each test class to have a separate report file,
but isn't limited to that. Solving these issues isn't easy and
probably not worth it, given that the only reason we started using
a single LauncherDiscoveryRequest is because it just seemed logical
and there is no other strong reason to do so. This commit switches
back to the behaviour that's been there in 1.10.5 version, to issue
multiple separate LauncherDiscoveryRequest(s) one each for the
test class that's selected through the use of <testclasses>.

src/etc/testcases/taskdefs/optional/junitlauncher.xml

@@ -131,12 +131,11 @@
     </target>
 
     <target name="test-batch" depends="init">
+        <property name="junitlauncher.test.tracker.append.file" value="${output.dir}/${test-batch.tracker}"/>
         <junitlauncher>
             <classpath refid="test.classpath"/>
             <testclasses outputdir="${output.dir}">
                 <listener classname="org.example.junitlauncher.Tracker"
-                          outputDir="${output.dir}"
-                          resultFile="${test-batch.tracker}"
                           if="test-batch.tracker"/>
 
                 <fileset dir="${build.classes.dir}">
@@ -216,6 +215,7 @@
         <!-- duplicate the Ant classes into a jar -->
         <jar destfile="${output.dir}/ant-runtime-duplicated.jar" basedir="${ant.runtime.classes.original.path}"/>
 
+        <property name="junitlauncher.test.tracker.append.file" value="${output.dir}/${test-ant-runtime-lib-custom-location.tracker}"/>
         <junitlauncher>
             <classpath>
                 <path refid="junit.engine.jupiter.classpath"/>
@@ -231,8 +231,6 @@
                     <include name="org/example/**/junitlauncher/**/"/>
                 </fileset>
                 <listener classname="org.example.junitlauncher.Tracker"
-                          outputDir="${output.dir}"
-                          resultFile="${test-ant-runtime-lib-custom-location.tracker}"
                           if="test-ant-runtime-lib-custom-location.tracker"/>
                 <fork dir="${basedir}" includeAntRuntimeLibraries="false">
                     <sysproperty key="junitlauncher.test.sysprop.one" value="forked"/>

src/main/org/apache/tools/ant/taskdefs/optional/junitlauncher/LauncherSupport.java

@@ -245,7 +245,23 @@ public class LauncherSupport {
 
     private Path getListenerOutputFile(final TestRequest testRequest, final ListenerDefinition listener) {
         final TestDefinition test = testRequest.getOwner();
-        final String filename = listener.requireResultFile(test);
+        final String filename;
+        if (listener.getResultFile() != null) {
+            filename = listener.getResultFile();
+        } else {
+            // compute a file name
+            final StringBuilder sb = new StringBuilder("TEST-");
+            sb.append(testRequest.getName() == null ? "unknown" : testRequest.getName());
+            sb.append(".");
+            final String suffix;
+            if ("org.apache.tools.ant.taskdefs.optional.junitlauncher.LegacyXmlResultFormatter".equals(listener.getClassName())) {
+                suffix = "xml";
+            } else {
+                suffix = "txt";
+            }
+            sb.append(suffix);
+            filename = sb.toString();
+        }
         if (listener.getOutputDir() != null) {
             // use the output dir defined on the listener
             return Paths.get(listener.getOutputDir(), filename);
@@ -391,19 +407,13 @@ public class LauncherSupport {
 
 
     private List<TestRequest> createTestRequests(final TestDefinition test) {
-        // create a TestRequest and add necessary selectors, filters to it
-        final LauncherDiscoveryRequestBuilder requestBuilder = LauncherDiscoveryRequestBuilder.request();
-        final TestRequest request = new TestRequest(test, requestBuilder);
-        addDiscoverySelectors(request);
-        addFilters(request);
-        return Collections.singletonList(request);
-    }
+        // create TestRequest(s) and add necessary selectors, filters to it
 
-    private void addDiscoverySelectors(final TestRequest testRequest) {
-        final TestDefinition test = testRequest.getOwner();
-        final LauncherDiscoveryRequestBuilder requestBuilder = testRequest.getDiscoveryRequest();
         if (test instanceof SingleTestClass) {
             final SingleTestClass singleTestClass = (SingleTestClass) test;
+            final LauncherDiscoveryRequestBuilder requestBuilder = LauncherDiscoveryRequestBuilder.request();
+            final TestRequest request = new TestRequest(test, requestBuilder);
+            request.setName(singleTestClass.getName());
             final String[] methods = singleTestClass.getMethods();
             if (methods == null) {
                 requestBuilder.selectors(DiscoverySelectors.selectClass(singleTestClass.getName()));
@@ -413,19 +423,28 @@ public class LauncherSupport {
                     requestBuilder.selectors(DiscoverySelectors.selectMethod(singleTestClass.getName(), method));
                 }
             }
-            return;
+            addFilters(request);
+            return Collections.singletonList(request);
         }
+
         if (test instanceof TestClasses) {
-            final TestClasses testClasses = (TestClasses) test;
-            final List<String> testClassNames = testClasses.getTestClassNames();
-            if (testClassNames.isEmpty()) {
-                return;
+            final List<String> testClasses = ((TestClasses) test).getTestClassNames();
+            if (testClasses.isEmpty()) {
+                return Collections.emptyList();
             }
-            for (final String testClass : testClassNames) {
+            final List<TestRequest> requests = new ArrayList<>();
+            for (final String testClass : testClasses) {
+                final LauncherDiscoveryRequestBuilder requestBuilder = LauncherDiscoveryRequestBuilder.request();
+                final TestRequest request = new TestRequest(test, requestBuilder);
+                request.setName(testClass);
                 requestBuilder.selectors(DiscoverySelectors.selectClass(testClass));
+                addFilters(request);
+
+                requests.add(request);
             }
-            return;
+            return requests;
         }
+        return Collections.emptyList();
     }
 
     /**

src/main/org/apache/tools/ant/taskdefs/optional/junitlauncher/TestRequest.java

@@ -36,7 +36,7 @@ final class TestRequest implements AutoCloseable {
     private final List<Closeable> closables = new ArrayList<>();
     private final List<TestResultFormatter> interestedInSysOut = new ArrayList<>();
     private final List<TestResultFormatter> interestedInSysErr = new ArrayList<>();
-
+    private String name;
 
     TestRequest(final TestDefinition ownerTest, final LauncherDiscoveryRequestBuilder discoveryRequest) {
         this.ownerTest = ownerTest;
@@ -51,6 +51,14 @@ final class TestRequest implements AutoCloseable {
         return discoveryRequest;
     }
 
+    void setName(final String name) {
+        this.name = name;
+    }
+
+    String getName() {
+        return this.name;
+    }
+
     void closeUponCompletion(final Closeable closeable) {
         if (closeable == null) {
             return;

src/main/org/apache/tools/ant/taskdefs/optional/junitlauncher/confined/ListenerDefinition.java

@@ -100,25 +100,8 @@ public class ListenerDefinition {
         this.resultFile = filename;
     }
 
-    public String requireResultFile(final TestDefinition test) {
-        if (this.resultFile != null) {
-            return this.resultFile;
-        }
-        final StringBuilder sb = new StringBuilder("TEST-");
-        if (test instanceof NamedTest) {
-            sb.append(((NamedTest) test).getName());
-        } else {
-            sb.append("unknown");
-        }
-        sb.append(".");
-        final String suffix;
-        if ("org.apache.tools.ant.taskdefs.optional.junitlauncher.LegacyXmlResultFormatter".equals(this.className)) {
-            suffix = "xml";
-        } else {
-            suffix = "txt";
-        }
-        sb.append(suffix);
-        return sb.toString();
+    public String getResultFile() {
+        return this.resultFile;
     }
 
     public void setSendSysOut(final boolean sendSysOut) {

src/tests/junit/org/example/junitlauncher/Tracker.java

@@ -25,11 +25,15 @@ import org.junit.platform.engine.support.descriptor.ClassSource;
 import org.junit.platform.engine.support.descriptor.MethodSource;
 import org.junit.platform.launcher.TestIdentifier;
 
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.nio.file.Files;
+import java.nio.file.OpenOption;
 import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
 import java.util.List;
 
 /**
@@ -45,10 +49,23 @@ public class Tracker implements TestResultFormatter {
 
     private PrintWriter writer;
     private TestExecutionContext context;
+    private OutputStream appendModeFile;
 
     @Override
     public void setDestination(final OutputStream os) {
-        this.writer = new PrintWriter(os, true);
+        final String propVal = this.context.getProperties().getProperty("junitlauncher.test.tracker.append.file");
+        if (propVal == null) {
+            this.writer = new PrintWriter(os, true);
+            return;
+        }
+        // ignore the passed outputstream and instead create our own, in append mode
+        final Path appendModeFilePath = Paths.get(propVal);
+        try {
+            this.appendModeFile = Files.newOutputStream(appendModeFilePath, StandardOpenOption.CREATE, StandardOpenOption.APPEND);
+            this.writer = new PrintWriter(this.appendModeFile, true);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
     }
 
     @Override
@@ -59,6 +76,9 @@ public class Tracker implements TestResultFormatter {
     @Override
     public void close() throws IOException {
         this.writer.flush();
+        if (this.appendModeFile != null) {
+            this.appendModeFile.close();
+        }
     }
 
     @Override