Add OpenTracingShimBuilder class and test

CHANGELOG.md

@@ -20,6 +20,7 @@ more details.
 - The shim now supports methods that take a timestamp as a parameter. 
 - You can now specify both the `TEXT_MAP` and the `HTTP_HEADER` type propagators for the shim. 
 See `io.opentelemetry.opentracingshim.OpenTracingPropagators` for details.
+- Add `OpenTracingShimBuilder` class to create the shim.
 
 ### Extensions
 

opentracing-shim/src/main/java/io/opentelemetry/opentracingshim/OpenTracingShim.java

@@ -11,6 +11,9 @@
 import io.opentelemetry.api.trace.TracerProvider;
 
 /**
+ * This class is deprecated. Please Use {@link OpenTracingShimBuilder} instead to create an
+ * OpenTracing {@link io.opentracing.Tracer} instance.
+ *
  * Factory for creating an OpenTracing {@link io.opentracing.Tracer} that is implemented using the
  * OpenTelemetry APIs.
  */

opentracing-shim/src/main/java/io/opentelemetry/opentracingshim/OpenTracingShimBuilder.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.opentracingshim;
+
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.trace.Tracer;
+import io.opentelemetry.api.trace.TracerProvider;
+import java.util.Objects;
+
+/** 
+ * Builder for creating an OpenTracing {@link io.opentracing.Tracer} that is implemented using the
+ * OpenTelemetry APIs.
+ */
+public class OpenTracingShimBuilder{
+    private Tracer tracer = getTracer(GlobalOpenTelemetry.getTracerProvider());
+    private OpenTracingPropagators propagators = OpenTracingPropagators.builder().build();
+
+    /** Returns a new {@code OpenTracingShimBuilder} instance. */
+    public static OpenTracingShimBuilder builder(){
+        return new OpenTracingShimBuilder();
+    }
+
+    /** Set a {@code Tracer} instance to create this shim. */
+    public OpenTracingShimBuilder setTracer(Tracer tracer){
+        Objects.requireNonNull(tracer, "tracer");
+        this.tracer = tracer;
+        return this;
+    }
+
+    /** Set a {@code OpenTracingPropagators} instance to create this shim. */
+    public OpenTracingShimBuilder setPropagators(OpenTracingPropagators propagators){
+        Objects.requireNonNull(propagators, "propagators");
+        this.propagators = propagators;
+        return this;
+    }
+
+    /**
+     * Set a {@code OpenTelemetry} instance to create this shim.
+     * The {@code Tracer} and {@code OpenTracingPropagators} instances required to
+     * create the shim will be obtained from the {@code OpenTelemetry}.
+     */
+    public OpenTracingShimBuilder setOpentelemetry(OpenTelemetry openTelemetry){
+        setTracer(getTracer(openTelemetry.getTracerProvider()));
+        setPropagators(OpenTracingPropagators.builder()
+            .setTextMap(openTelemetry.getPropagators().getTextMapPropagator())
+            .setHttpHeaders(openTelemetry.getPropagators().getTextMapPropagator())
+            .build());
+        return this;
+    }
+
+   /**
+    * Constructs a new instance of OpenTracing {@link io.opentracing.Tracer} based on the
+    * builder's values.
+    *
+    * @return a {@code io.opentracing.Tracer}.
+    */
+    public io.opentracing.Tracer build(){
+        return new TracerShim(new TelemetryInfo(tracer, propagators));
+    }
+
+    private static Tracer getTracer(TracerProvider tracerProvider) {
+        return tracerProvider.get("opentracingshim");
+    }
+}

opentracing-shim/src/test/java/io/opentelemetry/opentracingshim/OpenTracingShimBuilderTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.opentracingshim;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.trace.Tracer;
+import io.opentelemetry.context.propagation.ContextPropagators;
+import io.opentelemetry.context.propagation.TextMapPropagator;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+class OpenTracingShimBuilderTest {
+
+  @AfterEach
+  void tearDown() {
+    GlobalOpenTelemetry.resetForTest();
+  }
+
+  @Test
+  void openTracingShimBuilder_default() {
+    TracerShim tracerShim = (TracerShim) OpenTracingShimBuilder.builder().build();
+    assertThat(tracerShim.tracer()).isEqualTo(GlobalOpenTelemetry.getTracer("opentracingshim"));
+  }
+
+  @Test
+  void openTracingShimBuilder_fromOpenTelemetryInstance() {
+    OpenTelemetry openTelemetry = mock(OpenTelemetry.class);
+    SdkTracerProvider sdk = SdkTracerProvider.builder().build();
+    when(openTelemetry.getTracerProvider()).thenReturn(sdk);
+    ContextPropagators contextPropagators = mock(ContextPropagators.class);
+    when(contextPropagators.getTextMapPropagator()).thenReturn(mock(TextMapPropagator.class));
+    when(openTelemetry.getPropagators()).thenReturn(contextPropagators);
+
+    TracerShim tracerShim = (TracerShim) OpenTracingShimBuilder.builder().setOpentelemetry(openTelemetry).build();
+    assertThat(tracerShim.tracer()).isEqualTo(sdk.get("opentracingshim"));
+  }
+
+  @Test
+  void openTracingShimBuilder_withPropagators() {
+    Tracer tracer = mock(Tracer.class);
+
+    TextMapPropagator textMapPropagator = new CustomTextMapPropagator();
+    TextMapPropagator httpHeadersPropagator = new CustomTextMapPropagator();
+
+    TracerShim tracerShim =
+        (TracerShim)
+            OpenTracingShimBuilder
+                .builder()
+                .setTracer(tracer)
+                .setPropagators(
+                  OpenTracingPropagators
+                      .builder()
+                      .setTextMap(textMapPropagator)
+                      .setHttpHeaders(httpHeadersPropagator)
+                      .build())
+                .build();
+
+    assertThat(tracerShim.propagators().textMapPropagator()).isSameAs(textMapPropagator);
+    assertThat(tracerShim.propagators().httpHeadersPropagator()).isSameAs(httpHeadersPropagator);
+  }
+
+}