bugfix: add newline in stdout exporter (#6848)

exporters/common/src/main/java/io/opentelemetry/exporter/internal/marshal/Marshaler.java

@@ -38,6 +38,14 @@ public abstract class Marshaler {
     }
   }
 
+  /** Marshals into the {@link JsonGenerator} in proto JSON format and adds a newline. */
+  public final void writeJsonWithNewline(JsonGenerator output) throws IOException {
+    try (JsonSerializer serializer = new JsonSerializer(output)) {
+      serializer.writeMessageValue(this);
+      output.writeRaw('\n');
+    }
+  }
+
   /** Returns the number of bytes this Marshaler will write in proto binary format. */
   public abstract int getBinarySerializedSize();
 

exporters/logging-otlp/src/main/java/io/opentelemetry/exporter/logging/otlp/internal/writer/StreamJsonWriter.java

@@ -38,7 +38,7 @@ public class StreamJsonWriter implements JsonWriter {
   @Override
   public CompletableResultCode write(Marshaler exportRequest) {
     try {
-      exportRequest.writeJsonTo(
+      exportRequest.writeJsonWithNewline(
           JSON_FACTORY
               .createGenerator(outputStream)
               .disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET));

exporters/logging-otlp/src/test/java/io/opentelemetry/exporter/logging/otlp/AbstractOtlpStdoutExporterTest.java

@@ -34,7 +34,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
-import org.json.JSONException;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
@@ -57,6 +56,7 @@ abstract class AbstractOtlpStdoutExporterTest<T> {
   private static final PrintStream SYSTEM_OUT_PRINT_STREAM = new PrintStream(SYSTEM_OUT_STREAM);
 
   @RegisterExtension LogCapturer logs;
+  private int skipLogs;
   private final String defaultConfigString;
   private final TestDataExporter<? super T> testDataExporter;
   protected final Class<?> exporterClass;
@@ -87,6 +87,7 @@ abstract class AbstractOtlpStdoutExporterTest<T> {
   private String output(@Nullable OutputStream outputStream, @Nullable Path file) {
     if (outputStream == null) {
       return logs.getEvents().stream()
+          .skip(skipLogs)
           .map(LoggingEvent::getMessage)
           .reduce("", (a, b) -> a + b + "\n")
           .trim();
@@ -94,14 +95,14 @@ abstract class AbstractOtlpStdoutExporterTest<T> {
 
     if (file != null) {
       try {
-        return new String(Files.readAllBytes(file), StandardCharsets.UTF_8);
+        return new String(Files.readAllBytes(file), StandardCharsets.UTF_8).trim();
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
     }
 
     try {
-      return SYSTEM_OUT_STREAM.toString(StandardCharsets.UTF_8.name());
+      return SYSTEM_OUT_STREAM.toString(StandardCharsets.UTF_8.name()).trim();
     } catch (UnsupportedEncodingException e) {
       throw new RuntimeException(e);
     }
@@ -204,8 +205,7 @@ abstract class AbstractOtlpStdoutExporterTest<T> {
   @SuppressWarnings("SystemOut")
   @ParameterizedTest(name = "{0}")
   @MethodSource("exportTestCases")
-  void exportWithProgrammaticConfig(String name, TestCase testCase)
-      throws JSONException, IOException {
+  void exportWithProgrammaticConfig(String name, TestCase testCase) throws Exception {
     OutputStream outputStream;
     Path file = null;
     switch (testCase.getOutputType()) {
@@ -247,6 +247,26 @@ abstract class AbstractOtlpStdoutExporterTest<T> {
     if (testCase.isWrapperJsonObject()) {
       assertThat(output).doesNotContain("\n");
     }
+
+    if (file == null) {
+      // no need to test again for file - and it's not working with files
+      assertDoubleOutput(exporter, expectedJson, outputStream);
+    }
+  }
+
+  private void assertDoubleOutput(
+      Supplier<T> exporter, String expectedJson, @Nullable OutputStream outputStream)
+      throws Exception {
+    SYSTEM_OUT_STREAM.reset();
+    skipLogs = logs.getEvents().size();
+    testDataExporter.export(exporter.get());
+    testDataExporter.export(exporter.get());
+
+    String[] lines = output(outputStream, null).split("\n");
+    assertThat(lines).hasSize(2);
+    for (String line : lines) {
+      JSONAssert.assertEquals("Got \n" + line, expectedJson, line, false);
+    }
   }
 
   @Test

exporters/logging-otlp/src/test/java/io/opentelemetry/exporter/logging/otlp/internal/writer/StreamJsonWriterTest.java

@@ -46,7 +46,9 @@ class StreamJsonWriterTest {
   @Test
   void errorWriting() throws IOException {
     Marshaler marshaler = mock(Marshaler.class);
-    Mockito.doThrow(new IOException("test")).when(marshaler).writeJsonTo(any(JsonGenerator.class));
+    Mockito.doThrow(new IOException("test"))
+        .when(marshaler)
+        .writeJsonWithNewline(any(JsonGenerator.class));
 
     StreamJsonWriter writer = new StreamJsonWriter(System.out, "type");
     writer.write(marshaler);

exporters/prometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusMetricReaderTest.java

@@ -616,7 +616,7 @@ class PrometheusMetricReaderTest {
             + "        value: 7.0\n"
             + "        timestamp {\n"
             + "          seconds: <timestamp>\n"
-            + "          nanos: <timestamp>\n"
+            + "          <maybeNanos>\n"
             + "        }\n"
             + "      }\n"
             + "    }\n"
@@ -661,7 +661,7 @@ class PrometheusMetricReaderTest {
             + "        value: 3.0\n"
             + "        timestamp {\n"
             + "          seconds: <timestamp>\n"
-            + "          nanos: <timestamp>\n"
+            + "          <maybeNanos>\n"
             + "        }\n"
             + "      }\n"
             + "    }\n"
@@ -1115,7 +1115,9 @@ class PrometheusMetricReaderTest {
    */
   private static String toPattern(String expected) {
     Map<String, String> replacePatterns = new HashMap<>();
-    replacePatterns.put("timestamp", "[0-9]+(\\.[0-9]+)?");
+    String timestampPattern = "[0-9]+(\\.[0-9]+)?";
+    replacePatterns.put("timestamp", timestampPattern);
+    replacePatterns.put("maybeNanos", String.format("(nanos: %s)?", timestampPattern));
     replacePatterns.put("spanId", "[a-z0-9]*");
     replacePatterns.put("traceId", "[a-z0-9]*");
     replacePatterns.put("measurement", "[0-9\\.]*");