NPE during logging

filters/pom.xml

@@ -55,6 +55,11 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-params</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

filters/src/main/java/io/camunda/zeebe/process/test/filters/logger/RecordStreamLogger.java

@@ -53,7 +53,7 @@ public class RecordStreamLogger {
   private final Map<ValueType, Function<Record<?>, String>> valueTypeLoggers = new HashMap<>();
 
   public RecordStreamLogger(final RecordStreamSource recordStreamSource) {
-    this.recordStream = RecordStream.of(recordStreamSource);
+    recordStream = RecordStream.of(recordStreamSource);
     valueTypeLoggers.put(ValueType.JOB, this::logJobRecordValue);
     valueTypeLoggers.put(ValueType.DEPLOYMENT, this::logDeploymentRecordValue);
     valueTypeLoggers.put(ValueType.PROCESS_INSTANCE, this::logProcessInstanceRecordValue);
@@ -266,13 +266,13 @@ private String logProcessEventRecordValue(final Record<?> record) {
     return joiner.toString();
   }
 
-  private String logVariables(final Map<String, Object> variables) {
+  protected String logVariables(final Map<String, Object> variables) {
     if (variables.isEmpty()) {
       return "";
     }
 
     final StringJoiner joiner = new StringJoiner(", ", "[", "]");
-    variables.forEach((key, value) -> joiner.add(key + " -> " + value.toString()));
+    variables.forEach((key, value) -> joiner.add(key + " -> " + value));
     return String.format("(Variables: %s)", joiner);
   }
 

filters/src/test/java/io/camunda/zeebe/process/test/filters/logger/RecordStreamLoggerTest.java

@@ -15,16 +15,34 @@
  */
 package io.camunda.zeebe.process.test.filters.logger;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import io.camunda.zeebe.protocol.record.Record;
 import io.camunda.zeebe.protocol.record.ValueType;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.stream.Stream;
 import org.assertj.core.api.SoftAssertions;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 class RecordStreamLoggerTest {
 
+  private static final Map<String, Object> TYPED_TEST_VARIABLES = new HashMap<>();
+
+  static {
+    TYPED_TEST_VARIABLES.put("stringProperty", "stringValue");
+    TYPED_TEST_VARIABLES.put("numberProperty", 123);
+    TYPED_TEST_VARIABLES.put("booleanProperty", true);
+    TYPED_TEST_VARIABLES.put("complexProperty", Arrays.asList("Element 1", "Element 2"));
+    TYPED_TEST_VARIABLES.put("nullProperty", null);
+  }
+
   @Test
   void testAllValueTypesAreMapped() {
     final Map<ValueType, Function<Record<?>, String>> valueTypeLoggers =
@@ -41,4 +59,34 @@ void testAllValueTypesAreMapped() {
 
     softly.assertAll();
   }
+
+  @ParameterizedTest(name = "{0}")
+  @MethodSource("provideVariables")
+  void testLogVariable(final String key, final Object value) {
+    final RecordStreamLogger logger = new RecordStreamLogger(null);
+
+    final String result = logger.logVariables(Collections.singletonMap(key, value));
+
+    assertThat(result).isEqualTo(String.format("(Variables: [%s -> %s])", key, value));
+  }
+
+  @Test
+  void testLogMultipleVariables() {
+    final RecordStreamLogger logger = new RecordStreamLogger(null);
+
+    final String result = logger.logVariables(TYPED_TEST_VARIABLES);
+
+    assertThat(result)
+        .contains("Variables: ")
+        .contains("stringProperty -> stringValue")
+        .contains("numberProperty -> 123")
+        .contains("booleanProperty -> true")
+        .contains("complexProperty -> [Element 1, Element 2]")
+        .contains("nullProperty -> null");
+  }
+
+  private static Stream<Arguments> provideVariables() {
+    return TYPED_TEST_VARIABLES.entrySet().stream()
+        .map(entry -> Arguments.of(entry.getKey(), entry.getValue()));
+  }
 }

qa/src/test/java/io/camunda/zeebe/process/test/qa/abstracts/assertions/AbstractProcessInstanceAssertTest.java

@@ -50,6 +50,7 @@ public abstract class AbstractProcessInstanceAssertTest {
     TYPED_TEST_VARIABLES.put("numberProperty", 123);
     TYPED_TEST_VARIABLES.put("booleanProperty", true);
     TYPED_TEST_VARIABLES.put("complexProperty", Arrays.asList("Element 1", "Element 2"));
+    TYPED_TEST_VARIABLES.put("nullProperty", null);
   }
 
   // These tests are for testing assertions as well as examples for users