Added missing setup of SimpleTraceContext through SimpleTraceContextB…

…uilder

fixes gh-500

micrometer-tracing-tests/micrometer-tracing-test/src/main/java/io/micrometer/tracing/test/simple/SimpleTraceContextBuilder.java

@@ -25,29 +25,54 @@
  */
 public class SimpleTraceContextBuilder implements TraceContext.Builder {
 
+    private String traceId;
+
+    private String parentId;
+
+    private String spanId;
+
+    private Boolean sampled;
+
     @Override
     public TraceContext.Builder traceId(String traceId) {
+        this.traceId = traceId;
         return this;
     }
 
     @Override
     public TraceContext.Builder parentId(String parentId) {
+        this.parentId = parentId;
         return this;
     }
 
     @Override
     public TraceContext.Builder spanId(String spanId) {
+        this.spanId = spanId;
         return this;
     }
 
     @Override
     public TraceContext.Builder sampled(Boolean sampled) {
+        this.sampled = sampled;
         return this;
     }
 
     @Override
     public TraceContext build() {
-        return new SimpleTraceContext();
+        SimpleTraceContext traceContext = new SimpleTraceContext();
+        if (this.traceId != null) {
+            traceContext.setTraceId(this.traceId);
+        }
+        if (this.spanId != null) {
+            traceContext.setSpanId(this.spanId);
+        }
+        if (this.parentId != null) {
+            traceContext.setParentId(this.parentId);
+        }
+        if (this.sampled != null) {
+            traceContext.setSampled(this.sampled);
+        }
+        return traceContext;
     }
 
 }

micrometer-tracing-tests/micrometer-tracing-test/src/test/java/io/micrometer/tracing/test/simple/SimpleTraceContextBuilderTests.java

@@ -0,0 +1,52 @@
+/**
+ * Copyright 2023 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
+ *
+ * https://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 io.micrometer.tracing.test.simple;
+
+import io.micrometer.tracing.TraceContext;
+import org.assertj.core.api.SoftAssertions;
+import org.junit.jupiter.api.Test;
+
+class SimpleTraceContextBuilderTests {
+
+    @Test
+    void should_build_trace_context_through_builder_with_default_values() {
+        TraceContext traceContext = new SimpleTraceContextBuilder().build();
+
+        SoftAssertions.assertSoftly(softAssertions -> {
+            softAssertions.assertThat(traceContext.traceId()).isEmpty();
+            softAssertions.assertThat(traceContext.spanId()).isEmpty();
+            softAssertions.assertThat(traceContext.parentId()).isEmpty();
+            softAssertions.assertThat(traceContext.sampled()).isFalse();
+        });
+    }
+
+    @Test
+    void should_build_trace_context_through_builder_with_overridden_values() {
+        TraceContext traceContext = new SimpleTraceContextBuilder().traceId("1")
+            .spanId("2")
+            .parentId("3")
+            .sampled(true)
+            .build();
+
+        SoftAssertions.assertSoftly(softAssertions -> {
+            softAssertions.assertThat(traceContext.traceId()).isEqualTo("1");
+            softAssertions.assertThat(traceContext.spanId()).isEqualTo("2");
+            softAssertions.assertThat(traceContext.parentId()).isEqualTo("3");
+            softAssertions.assertThat(traceContext.sampled()).isTrue();
+        });
+    }
+
+}