Use RestTestClient rather than REST Assured

Closes gh-47686

module/spring-boot-micrometer-metrics/build.gradle

@@ -66,7 +66,8 @@ dependencies {
 
 	dockerTestImplementation(project(":test-support:spring-boot-docker-test-support"))
 	dockerTestImplementation(testFixtures(project(":core:spring-boot-docker-compose")))
-	dockerTestImplementation("io.rest-assured:rest-assured")
+	dockerTestImplementation("org.apache.httpcomponents.client5:httpclient5")
+	dockerTestImplementation("org.springframework:spring-web")
 	dockerTestImplementation("org.testcontainers:testcontainers-junit-jupiter")
 
 	testFixturesImplementation(project(":test-support:spring-boot-test-support"))

module/spring-boot-micrometer-metrics/src/dockerTest/java/org/springframework/boot/micrometer/metrics/testcontainers/otlp/GrafanaOpenTelemetryMetricsContainerConnectionDetailsFactoryIntegrationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.micrometer.metrics.testcontainers.otlp;
 
+import java.net.URI;
 import java.time.Duration;
 
 import io.micrometer.core.instrument.Clock;
@@ -24,8 +25,6 @@ import io.micrometer.core.instrument.DistributionSummary;
 import io.micrometer.core.instrument.Gauge;
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Timer;
-import io.restassured.RestAssured;
-import io.restassured.response.Response;
 import org.awaitility.Awaitility;
 import org.junit.jupiter.api.Test;
 import org.testcontainers.grafana.LgtmStackContainer;
@@ -41,8 +40,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.test.context.TestPropertySource;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
-
-import static org.assertj.core.api.Assertions.assertThat;
+import org.springframework.test.web.servlet.client.RestTestClient;
 
 /**
  * Tests for {@link GrafanaOpenTelemetryMetricsContainerConnectionDetailsFactory}.
@@ -68,53 +66,39 @@ class GrafanaOpenTelemetryMetricsContainerConnectionDetailsFactoryIntegrationTes
 		Gauge.builder("test.gauge", () -> 12).register(this.meterRegistry);
 		Timer.builder("test.timer").register(this.meterRegistry).record(Duration.ofMillis(123));
 		DistributionSummary.builder("test.distributionsummary").register(this.meterRegistry).record(24);
-
 		Awaitility.given()
 			.pollInterval(Duration.ofSeconds(2))
 			.atMost(Duration.ofSeconds(10))
 			.ignoreExceptions()
 			.untilAsserted(() -> {
-				Response response = RestAssured.given()
-					.queryParam("query", "{job=\"test\"}")
-					.get("%s/api/v1/query".formatted(container.getPrometheusHttpUrl()))
-					.prettyPeek()
-					.thenReturn();
-				assertThat(response.getStatusCode()).isEqualTo(200);
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_counter_total' }.value")).contains("42");
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_gauge' }.value")).contains("12");
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_timer_milliseconds_count' }.value"))
-					.contains("1");
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_timer_milliseconds_sum' }.value"))
-					.contains("123");
-				assertThat(response.body()
-					.jsonPath()
-					.getList(
-							"data.result.find { it.metric.__name__ == 'test_timer_milliseconds_bucket' & it.metric.le == '+Inf' }.value"))
-					.contains("1");
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_distributionsummary_count' }.value"))
-					.contains("1");
-				assertThat(response.body()
-					.jsonPath()
-					.getList("data.result.find { it.metric.__name__ == 'test_distributionsummary_sum' }.value"))
-					.contains("24");
-				assertThat(response.body()
-					.jsonPath()
-					.getList(
-							"data.result.find { it.metric.__name__ == 'test_distributionsummary_bucket' & it.metric.le == '+Inf' }.value"))
-					.contains("1");
+				RestTestClient restClient = RestTestClient.bindToServer().build();
+				restClient.get()
+					.uri(URI.create(container.getPrometheusHttpUrl() + "/api/v1/query?query=%7Bjob=%22test%22%7D"))
+					.exchange()
+					.expectStatus()
+					.isOk()
+					.expectBody()
+					.jsonPath(metricWithValue("test_counter_total", "42"))
+					.exists()
+					.jsonPath(metricWithValue("test_timer_milliseconds_count", "1"))
+					.exists()
+					.jsonPath(metricWithValue("test_timer_milliseconds_sum", "123"))
+					.exists()
+					.jsonPath(metricWithValue("test_timer_milliseconds_bucket", "1"))
+					.exists()
+					.jsonPath(metricWithValue("test_distributionsummary_count", "1"))
+					.exists()
+					.jsonPath(metricWithValue("test_distributionsummary_sum", "24"))
+					.exists()
+					.jsonPath(metricWithValue("test_distributionsummary_bucket", "1"))
+					.exists();
 			});
 	}
 
+	private String metricWithValue(String metric, String value) {
+		return "$.data.result[?(@.metric.__name__==\"%s\" && \"%s\" in @.value)]".formatted(metric, value);
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@ImportAutoConfiguration(OtlpMetricsExportAutoConfiguration.class)
 	static class TestConfiguration {

module/spring-boot-micrometer-metrics/src/dockerTest/java/org/springframework/boot/micrometer/metrics/testcontainers/otlp/OpenTelemetryMetricsContainerConnectionDetailsFactoryIntegrationTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.micrometer.metrics.testcontainers.otlp;
 
 import java.time.Duration;
+import java.util.function.Consumer;
 
 import io.micrometer.core.instrument.Clock;
 import io.micrometer.core.instrument.Counter;
@@ -24,9 +25,8 @@ import io.micrometer.core.instrument.DistributionSummary;
 import io.micrometer.core.instrument.Gauge;
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Timer;
-import io.restassured.RestAssured;
-import io.restassured.response.Response;
 import org.awaitility.Awaitility;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.testcontainers.containers.GenericContainer;
 import org.testcontainers.junit.jupiter.Container;
@@ -40,12 +40,13 @@ import org.springframework.boot.testcontainers.service.connection.ServiceConnect
 import org.springframework.boot.testsupport.container.TestImage;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.MediaType;
 import org.springframework.test.context.TestPropertySource;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+import org.springframework.test.web.servlet.client.RestTestClient;
+import org.springframework.test.web.servlet.client.RestTestClient.ResponseSpec;
 
-import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.endsWith;
-import static org.hamcrest.Matchers.matchesPattern;
+import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * Tests for {@link OpenTelemetryMetricsContainerConnectionDetailsFactory}.
@@ -59,7 +60,8 @@ import static org.hamcrest.Matchers.matchesPattern;
 @Testcontainers(disabledWithoutDocker = true)
 class OpenTelemetryMetricsContainerConnectionDetailsFactoryIntegrationTests {
 
-	private static final String OPENMETRICS_001 = "application/openmetrics-text; version=0.0.1; charset=utf-8";
+	private static final MediaType OPENMETRICS_001 = MediaType
+		.parseMediaType("application/openmetrics-text; version=0.0.1; charset=utf-8");
 
 	private static final String CONFIG_FILE_NAME = "collector-config.yml";
 
@@ -81,23 +83,33 @@ class OpenTelemetryMetricsContainerConnectionDetailsFactoryIntegrationTests {
 		DistributionSummary.builder("test.distributionsummary").register(this.meterRegistry).record(24);
 		Awaitility.await()
 			.atMost(Duration.ofSeconds(30))
-			.untilAsserted(() -> whenPrometheusScraped().then()
-				.statusCode(200)
+			.untilAsserted(() -> whenPrometheusScraped().expectStatus()
+				.isOk()
+				.expectHeader()
 				.contentType(OPENMETRICS_001)
-				.body(endsWith("# EOF\n"), containsString(
-						"{job=\"test\",service_name=\"test\",telemetry_sdk_language=\"java\",telemetry_sdk_name=\"io.micrometer\""),
-						matchesPattern("(?s)^.*test_counter\\{.+} 42\\.0\\n.*$"),
-						matchesPattern("(?s)^.*test_gauge\\{.+} 12\\.0\\n.*$"),
-						matchesPattern("(?s)^.*test_timer_count\\{.+} 1\\n.*$"),
-						matchesPattern("(?s)^.*test_timer_sum\\{.+} 123\\.0\\n.*$"),
-						matchesPattern("(?s)^.*test_timer_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$"),
-						matchesPattern("(?s)^.*test_distributionsummary_count\\{.+} 1\\n.*$"),
-						matchesPattern("(?s)^.*test_distributionsummary_sum\\{.+} 24\\.0\\n.*$"),
-						matchesPattern("(?s)^.*test_distributionsummary_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$")));
+				.expectBody(String.class)
+				.value((Consumer<@Nullable String>) (body) -> assertThat(body).endsWith("# EOF\n")
+					.contains(
+							"{job=\"test\",service_name=\"test\",telemetry_sdk_language=\"java\",telemetry_sdk_name=\"io.micrometer\"")
+					.matches("(?s)^.*test_counter\\{.+} 42\\.0\\n.*$")
+					.matches("(?s)^.*test_gauge\\{.+} 12\\.0\\n.*$")
+					.matches("(?s)^.*test_timer_count\\{.+} 1\\n.*$")
+					.matches("(?s)^.*test_timer_sum\\{.+} 123\\.0\\n.*$")
+					.matches("(?s)^.*test_timer_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$")
+					.matches("(?s)^.*test_distributionsummary_count\\{.+} 1\\n.*$")
+					.matches("(?s)^.*test_distributionsummary_sum\\{.+} 24\\.0\\n.*$")
+					.matches("(?s)^.*test_distributionsummary_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$")));
+
 	}
 
-	private Response whenPrometheusScraped() {
-		return RestAssured.given().port(container.getMappedPort(9090)).accept(OPENMETRICS_001).when().get("/metrics");
+	private ResponseSpec whenPrometheusScraped() {
+		return RestTestClient.bindToServer()
+			.baseUrl("http://" + container.getHost() + ":" + container.getMappedPort(9090))
+			.build()
+			.get()
+			.uri("/metrics")
+			.accept(OPENMETRICS_001)
+			.exchange();
 	}
 
 	@Configuration(proxyBeanMethods = false)