Merge branch 'null-spantag-parameter' of https://github.com/bedla/spring-cloud-sleuth into bedla-null-spantag-parameter

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/annotation/SpanTagAnnotationHandler.java

@@ -146,19 +146,20 @@ class SpanTagAnnotationHandler {
 	}
 
 	String resolveTagValue(SpanTag annotation, Object argument) {
-		if (argument == null) {
-			return "";
-		}
+		String value = null;
 		if (annotation.resolver() != NoOpTagValueResolver.class) {
 			TagValueResolver tagValueResolver = this.beanFactory
 					.getBean(annotation.resolver());
-			return tagValueResolver.resolve(argument);
+			value = tagValueResolver.resolve(argument);
 		}
 		else if (StringUtils.hasText(annotation.expression())) {
-			return this.beanFactory.getBean(TagValueExpressionResolver.class)
+			value = this.beanFactory.getBean(TagValueExpressionResolver.class)
 					.resolve(annotation.expression(), argument);
 		}
-		return argument.toString();
+		else if (argument != null) {
+			value = argument.toString();
+		}
+		return value == null ? "" : value;
 	}
 
 }

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/annotation/NullSpanTagAnnotationHandlerTests.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright 2013-2019 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
+ *
+ *      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 org.springframework.cloud.sleuth.annotation;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+
+import brave.sampler.Sampler;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+@SpringBootTest(classes = NullSpanTagAnnotationHandlerTests.TestConfiguration.class)
+
+public class NullSpanTagAnnotationHandlerTests {
+
+	@Autowired
+	BeanFactory beanFactory;
+
+	@Autowired
+	TagValueResolver tagValueResolver;
+
+	SpanTagAnnotationHandler handler;
+
+	@BeforeEach
+	public void setup() {
+		this.handler = new SpanTagAnnotationHandler(this.beanFactory);
+	}
+
+	@Test
+	public void shouldUseEmptyStringWheCustomTagValueResolverReturnsNull()
+			throws NoSuchMethodException, SecurityException {
+		Method method = AnnotationMockClass.class
+				.getMethod("getAnnotationForTagValueResolver", String.class);
+		Annotation annotation = method.getParameterAnnotations()[0][0];
+		if (annotation instanceof SpanTag) {
+			String resolvedValue = this.handler.resolveTagValue((SpanTag) annotation,
+					"test");
+			assertThat(resolvedValue).isEqualTo("");
+		}
+		else {
+			fail("Annotation was not SleuthSpanTag");
+		}
+	}
+
+	@Test
+	public void shouldUseEmptyStringWhenTagValueExpressionReturnNull()
+			throws NoSuchMethodException, SecurityException {
+		Method method = AnnotationMockClass.class
+				.getMethod("getAnnotationForTagValueExpression", String.class);
+		Annotation annotation = method.getParameterAnnotations()[0][0];
+		if (annotation instanceof SpanTag) {
+			String resolvedValue = this.handler.resolveTagValue((SpanTag) annotation,
+					"test");
+
+			assertThat(resolvedValue).isEqualTo("");
+		}
+		else {
+			fail("Annotation was not SleuthSpanTag");
+		}
+	}
+
+	@Test
+	public void shouldUseEmptyStringWhenArgumentIsNull()
+			throws NoSuchMethodException, SecurityException {
+		Method method = AnnotationMockClass.class
+				.getMethod("getAnnotationForArgumentToString", Long.class);
+		Annotation annotation = method.getParameterAnnotations()[0][0];
+		if (annotation instanceof SpanTag) {
+			String resolvedValue = this.handler.resolveTagValue((SpanTag) annotation,
+					null);
+			assertThat(resolvedValue).isEqualTo("");
+		}
+		else {
+			fail("Annotation was not SleuthSpanTag");
+		}
+	}
+
+	@Configuration
+	@EnableAutoConfiguration
+	protected static class TestConfiguration {
+
+		@Bean
+		public TagValueResolver tagValueResolver() {
+			return parameter -> null;
+		}
+
+		@Bean
+		Sampler alwaysSampler() {
+			return Sampler.ALWAYS_SAMPLE;
+		}
+
+	}
+
+	protected class AnnotationMockClass {
+
+		@NewSpan
+		public void getAnnotationForTagValueResolver(
+				@SpanTag(key = "test", resolver = TagValueResolver.class) String test) {
+		}
+
+		@NewSpan
+		public void getAnnotationForTagValueExpression(
+				@SpanTag(key = "test", expression = "null") String test) {
+		}
+
+		@NewSpan
+		public void getAnnotationForArgumentToString(@SpanTag("test") Long param) {
+		}
+
+	}
+
+}

tests/spring-cloud-sleuth-instrumentation-mvc-tests/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceFilterWebIntegrationTests.java

@@ -47,6 +47,8 @@ import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.system.CapturedOutput;
 import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.cloud.sleuth.annotation.ContinueSpan;
+import org.springframework.cloud.sleuth.annotation.SpanTag;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
@@ -54,6 +56,7 @@ import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.client.DefaultResponseErrorHandler;
 import org.springframework.web.client.HttpClientErrorException;
@@ -95,6 +98,24 @@ public class TraceFilterWebIntegrationTests {
 		then(spanHandler.takeRemoteSpan(Kind.SERVER).tags()).containsKey("http.url");
 	}
 
+	@Test
+	public void should_tag_with_value_from_null_expression() {
+		new RestTemplate().getForObject("http://localhost:" + port() + "/null-parameter",
+				String.class);
+
+		then(this.currentTraceContext.get()).isNull();
+		then(spanHandler.takeRemoteSpan(Kind.SERVER).tags()).containsEntry("foo", "1001");
+	}
+
+	@Test
+	public void should_tag_with_value_from_non_null_expression() {
+		new RestTemplate().getForObject(
+				"http://localhost:" + port() + "/null-parameter?bar=10", String.class);
+
+		then(this.currentTraceContext.get()).isNull();
+		then(spanHandler.takeRemoteSpan(Kind.SERVER).tags()).containsEntry("foo", "11");
+	}
+
 	@Test
 	public void exception_logging_span_handler_logs_synchronous_exceptions(
 			CapturedOutput capture) {
@@ -164,6 +185,11 @@ public class TraceFilterWebIntegrationTests {
 			return new GoodController();
 		}
 
+		@Bean
+		NullParameterController nullParameterController() {
+			return new NullParameterController();
+		}
+
 		@Bean
 		ExceptionThrowingController badController() {
 			return new ExceptionThrowingController();
@@ -258,6 +284,19 @@ public class TraceFilterWebIntegrationTests {
 
 	}
 
+	@RestController
+	public static class NullParameterController {
+
+		@RequestMapping("/null-parameter")
+		@ContinueSpan
+		public String nullParameter(
+				@SpanTag(key = "foo", expression = "(#root?:1000)+1") @RequestParam(
+						value = "bar", required = false) Integer param) {
+			return "ok param=" + param;
+		}
+
+	}
+
 	@RestController
 	public static class ExceptionThrowingController {