Add zipkin auto-configuration tests

See spring-projectsgh-30156

Author: mhalbritter

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/ZipkinAutoConfigurationTests.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2012-2022 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.boot.actuate.autoconfigure.tracing;
+
+import io.opentelemetry.exporter.zipkin.ZipkinSpanExporter;
+import org.junit.jupiter.api.Test;
+import zipkin2.reporter.Sender;
+import zipkin2.reporter.brave.ZipkinSpanHandler;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link ZipkinAutoConfiguration}.
+ *
+ * @author Moritz Halbritter
+ */
+class ZipkinAutoConfigurationTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+			.withConfiguration(AutoConfigurations.of(ZipkinAutoConfiguration.class));
+
+	@Test
+	void shouldNotFailIfZipkinIsMissing() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader("zipkin2"))
+				.run((context) -> assertThat(context).doesNotHaveBean(Sender.class));
+	}
+
+	@Test
+	void shouldNotFailIfZipkinUrlConnectionIsMissing() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader("zipkin2.reporter.urlconnection"))
+				.run((context) -> assertThat(context).doesNotHaveBean(Sender.class));
+	}
+
+	@Test
+	void shouldNotFailIfZipkinBraveIsMissing() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader("zipkin2.reporter.brave"))
+				.run((context) -> assertThat(context).doesNotHaveBean(ZipkinSpanHandler.class));
+	}
+
+	@Test
+	void shouldNotFailIfZipkinOpenTelemetryIsMissing() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader("io.opentelemetry.exporter.zipkin"))
+				.run((context) -> assertThat(context).doesNotHaveBean(ZipkinSpanExporter.class));
+	}
+
+}