Cypress Testing Integrated with Gradle and Spring Boot

dependencies {
	implementation(platform("org.testcontainers:testcontainers-bom:1.16.0"))
	testImplementation "org.testcontainers:testcontainers"
}

task yarnCypressVersion(type: YarnTask) {
	args = ['cypress', '--version']
}

# ?TC_TMPFS=/var/lib/postgresql/data:rw is a performance optimization to use a tmpfs for postgres data accelerating startup/runtime, see https://www.testcontainers.org/modules/databases/jdbc/
internal.datasource.url: jdbc:tc:postgresql:11:///?TC_TMPFS=/var/lib/postgresql/data:rw
spring.datasource.url: ${internal.datasource.url}

import static org.assertj.core.api.Assertions.assertThat;

import java.io.File;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.time.Duration;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.util.Assert;
import org.springframework.util.StreamUtils;
import org.testcontainers.Testcontainers;
import org.testcontainers.containers.BindMode;
import org.testcontainers.containers.GenericContainer;
import org.testcontainers.containers.SelinuxContext;
import org.testcontainers.containers.output.Slf4jLogConsumer;
import org.testcontainers.containers.startupcheck.OneShotStartupCheckStrategy;

import lombok.extern.slf4j.Slf4j;

// if the Cypress tests end up writing to the database, a separate database instance must be used to ensure this test doesn't pollute the expected database state of other tests that run after it. &TC_REUSABLE=true ensures that.
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = {"spring.datasource.url=${internal.datasource.url}&TC_REUSABLE=true"})
@Slf4j
/* default */ class CypressTest {
	@LocalServerPort
	private int port;

	private static String cypressVersion;

	@BeforeAll
	private static void beforeAll() throws Exception {
		cypressVersion = getCypressVersion();
		log.info("Tests will run using Cypress version {}", cypressVersion);
	}

	@Test
	/* default */ void testCypress() throws Exception {
		Testcontainers.exposeHostPorts(port); // allow the container to access the running web application
		try (GenericContainer<?> container = new GenericContainer<>("cypress/included:" + cypressVersion)) {
			container.addFileSystemBind(Path.of(".").toAbsolutePath().toString(), "/src", BindMode.READ_WRITE, SelinuxContext.SHARED);
			container
				.withLogConsumer(new Slf4jLogConsumer(log))
				.withEnv("CYPRESS_baseUrl", String.format("https://%s:%d", GenericContainer.INTERNAL_HOST_HOSTNAME, port))
				.withWorkingDirectory("/src/frontend")
				.withStartupCheckStrategy(
						new OneShotStartupCheckStrategy().withTimeout(Duration.ofHours(1))
						).start();
			assertThat(container.getLogs()).contains("All specs passed!");
		}
	}

	/** Get the installed version of Cypress.
	 *
	 * This approach ensures that as the version of Cypress specified in package management changes,
	 * this tests will always use the same version.
	 * @return installed version of Cypress.
	 * @throws Exception if something goes wrong
	 */
	private static String getCypressVersion() throws Exception {
		String cmd = "./gradlew";
		if (System.getProperty("os.name").startsWith("Win")) {
			cmd = "./gradlew.bat";
		}
		final Process process = Runtime.getRuntime().exec(new String[]{cmd, "yarnCypressVersion"}, null, new File("."));
		Assert.state(process.waitFor() == 0,"Cypress version command did not complete successfully");
		final String output = StreamUtils.copyToString(process.getInputStream(), StandardCharsets.UTF_8);
		final Matcher matcher = Pattern.compile("Cypress package version: (?<version>\\d++(?:\\.\\d++)++)").matcher(output);
		Assert.state(matcher.find(), "Could not determine Cypress version from command output. Output: " + output);
		return matcher.group("version");
	}
}