Output received messages on JVM test failure

client/src/main/java/org/mvndaemon/mvnd/client/DefaultClient.java

@@ -366,11 +366,11 @@ private DefaultResult(List<String> args, Exception exception, int exitCode) {
         @Override
         public ExecutionResult assertSuccess() {
             if (exception != null) {
-                throw new AssertionError(appendCommand(new StringBuilder("Build failed: ")).toString(), exception);
+                throw new AssertionError(ExecutionResult.appendCommand(new StringBuilder("Build failed: "), args).toString(), exception);
             }
             if (exitCode != 0) {
                 throw new AssertionError(
-                        appendCommand(new StringBuilder("Build exited with non-zero exit code " + exitCode + ": ")).toString(),
+                        ExecutionResult.appendCommand(new StringBuilder("Build exited with non-zero exit code " + exitCode + ": "), args).toString(),
                         exception);
             }
             return this;
@@ -379,7 +379,7 @@ public ExecutionResult assertSuccess() {
         @Override
         public ExecutionResult assertFailure() {
             if (exception == null && exitCode == 0) {
-                throw new AssertionError(appendCommand(new StringBuilder("Build did not fail: ")));
+                throw new AssertionError(ExecutionResult.appendCommand(new StringBuilder("Build did not fail: "), args));
             }
             return this;
         }
@@ -394,13 +394,6 @@ public boolean isSuccess() {
             return exception == null;
         }
 
-        StringBuilder appendCommand(StringBuilder sb) {
-            sb.append("mvnd");
-            for (String arg : args) {
-                sb.append(" \"").append(arg).append('"');
-            }
-            return sb;
-        }
     }
 
 }

client/src/main/java/org/mvndaemon/mvnd/client/ExecutionResult.java

@@ -15,6 +15,8 @@
  */
 package org.mvndaemon.mvnd.client;
 
+import java.util.List;
+
 /**
  * A result of a {@code mvnd} build.
  */
@@ -28,4 +30,12 @@ public interface ExecutionResult {
 
     int getExitCode();
 
+    public static StringBuilder appendCommand(StringBuilder sb, List<String> args) {
+        sb.append("mvnd");
+        for (String arg : args) {
+            sb.append(" \"").append(arg).append('"');
+        }
+        return sb;
+    }
+
 }

integration-tests/src/test/java/org/mvndaemon/mvnd/junit/JvmTestClient.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.mvndaemon.mvnd.junit;
+
+import java.util.List;
+import org.mvndaemon.mvnd.assertj.TestClientOutput;
+import org.mvndaemon.mvnd.client.DaemonParameters;
+import org.mvndaemon.mvnd.client.DefaultClient;
+import org.mvndaemon.mvnd.client.ExecutionResult;
+import org.mvndaemon.mvnd.common.logging.ClientOutput;
+
+public class JvmTestClient extends DefaultClient {
+
+    public JvmTestClient(DaemonParameters parameters) {
+        super(parameters);
+    }
+
+    @Override
+    public ExecutionResult execute(ClientOutput output, List<String> argv) {
+        final ExecutionResult delegate = super.execute(output, argv);
+        if (output instanceof TestClientOutput) {
+            return new JvmTestResult(delegate, ((TestClientOutput) output).messagesToString());
+        }
+        return delegate;
+    }
+
+    public static class JvmTestResult implements ExecutionResult {
+
+        private final ExecutionResult delegate;
+        private final List<String> log;
+
+        public JvmTestResult(ExecutionResult delegate, List<String> log) {
+            this.delegate = delegate;
+            this.log = log;
+        }
+
+        @Override
+        public JvmTestResult assertFailure() {
+            try {
+                delegate.assertFailure();
+            } catch (AssertionError e) {
+                final StringBuilder sb = new StringBuilder(e.getMessage());
+                sb.append("\n--- received messages start ---");
+                synchronized (log) {
+                    log.forEach(s -> sb.append('\n').append(s));
+                }
+                sb.append("\n--- received messages end ---");
+                throw new AssertionError(sb);
+            }
+            return this;
+        }
+
+        @Override
+        public JvmTestResult assertSuccess() {
+            try {
+                delegate.assertSuccess();
+            } catch (AssertionError e) {
+                final StringBuilder sb = new StringBuilder(e.getMessage());
+                sb.append("\n--- received messages start ---");
+                synchronized (log) {
+                    log.forEach(s -> sb.append('\n').append(s));
+                }
+                sb.append("\n--- received messages end ---");
+                throw new AssertionError(sb);
+            }
+            return this;
+        }
+
+        @Override
+        public int getExitCode() {
+            return delegate.getExitCode();
+        }
+
+        @Override
+        public boolean isSuccess() {
+            return delegate.isSuccess();
+        }
+
+    }
+
+}

integration-tests/src/test/java/org/mvndaemon/mvnd/junit/MvndTestExtension.java

@@ -32,7 +32,6 @@
 import org.junit.jupiter.api.extension.ExtensionContext.Store;
 import org.mvndaemon.mvnd.client.Client;
 import org.mvndaemon.mvnd.client.DaemonParameters;
-import org.mvndaemon.mvnd.client.DefaultClient;
 import org.mvndaemon.mvnd.common.DaemonRegistry;
 import org.mvndaemon.mvnd.common.Environment;
 import org.mvndaemon.mvnd.common.TimeUtils;
@@ -122,7 +121,7 @@ Client newClient(boolean isNative, DaemonParameters parameters, long timeoutMs)
             }
             return new NativeTestClient(parameters, mvndNativeExecutablePath, timeoutMs);
         } else {
-            return new DefaultClient(parameters);
+            return new JvmTestClient(parameters);
         }
     }
 

integration-tests/src/test/java/org/mvndaemon/mvnd/junit/NativeTestClient.java

@@ -113,27 +113,28 @@ public Result(List<String> args, int exitCode, List<String> log) {
             this.log = log;
         }
 
-        StringBuilder appendCommand(StringBuilder sb) {
-            for (String arg : args) {
-                sb.append(" \"").append(arg).append('"');
-            }
-            return sb;
-
-        }
-
         @Override
         public Result assertFailure() {
             if (exitCode == 0) {
-                throw new AssertionError(appendCommand(
-                        new StringBuilder("mvnd returned ").append(exitCode).append(" instead of non-zero exit code: ")));
+                final StringBuilder sb = ExecutionResult.appendCommand(
+                        new StringBuilder("mvnd returned ").append(exitCode).append(" instead of non-zero exit code: "),
+                        args);
+                sb.append("\n--- stderr+stdout start ---");
+                synchronized (log) {
+                    log.forEach(s -> sb.append('\n').append(s));
+                }
+                sb.append("\n--- stderr+stdout end ---");
+                throw new AssertionError(sb);
             }
             return this;
         }
 
         @Override
         public Result assertSuccess() {
             if (exitCode != 0) {
-                final StringBuilder sb = appendCommand(new StringBuilder("mvnd returned ").append(exitCode));
+                final StringBuilder sb = ExecutionResult.appendCommand(
+                        new StringBuilder("mvnd returned ").append(exitCode),
+                        args);
                 if (exitCode == CommandProcess.TIMEOUT_EXIT_CODE) {
                     sb.append(" (timeout)");
                 }