use @Slf4j (+logback) for logging instead of System.out/err.println (#165)

Co-authored-by: Michael Hoennig <michael@hoennig.de>
Reviewed-on: https://dev.hostsharing.net/hostsharing/hs.hsadmin.ng/pulls/165
Reviewed-by: Marc Sandlus <marc.sandlus@hostsharing.net>

src/test/java/net/hostsharing/hsadminng/config/CasAuthenticationFilterIntegrationTest.java

@@ -1,11 +1,16 @@
 package net.hostsharing.hsadminng.config;
 
 import com.github.tomakehurst.wiremock.WireMockServer;
+import net.hostsharing.hsadminng.test.LogbackLogPattern;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.logging.LogLevel;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
 import org.springframework.boot.test.web.client.TestRestTemplate;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpMethod;
@@ -13,15 +18,23 @@ import org.springframework.http.HttpStatus;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.TestPropertySource;
 
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.get;
+import static com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo;
 import static net.hostsharing.hsadminng.config.HttpHeadersBuilder.headers;
 import static org.apache.commons.lang3.RandomStringUtils.randomAlphanumeric;
 import static org.assertj.core.api.Assertions.assertThat;
-import static com.github.tomakehurst.wiremock.client.WireMock.*;
 
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
-@TestPropertySource(properties = {"server.port=0", "hsadminng.cas.server=http://localhost:8088"})
+@TestPropertySource(properties = {
+        "server.port=0",
+        "hsadminng.cas.server=http://localhost:8088",
+
+        "logging.level.root=DEBUG"
+})
 @ActiveProfiles({"wiremock", "realCasAuthenticator"}) // IMPORTANT: To test prod config, do NOT use test profile!
 @Tag("generalIntegrationTest")
+@ExtendWith(OutputCaptureExtension.class)
 class CasAuthenticationFilterIntegrationTest {
 
     @Value("${local.server.port}")
@@ -37,7 +50,7 @@ class CasAuthenticationFilterIntegrationTest {
     private WireMockServer wireMockServer;
 
     @Test
-    public void shouldAcceptRequestWithValidCasTicket() {
+    public void shouldAcceptRequestWithValidCasTicket(final CapturedOutput capturedOutput) {
         // given
         final var username = "test-user-" + randomAlphanumeric(4);
         wireMockServer.stubFor(get(urlEqualTo("/cas/p3/serviceValidate?service=" + serviceUrl + "&ticket=ST-valid"))
@@ -63,6 +76,9 @@ class CasAuthenticationFilterIntegrationTest {
         // then
         assertThat(result.getStatusCode()).isEqualTo(HttpStatus.OK);
         assertThat(result.getBody()).isEqualTo("pong " + username + "\n");
+        // HOWTO assert log messages
+        assertThat(capturedOutput.getOut()).containsPattern(
+                LogbackLogPattern.of(LogLevel.DEBUG, RealCasAuthenticator.class, "CAS-user: " + username));
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/errors/RestResponseEntityExceptionHandlerUnitTest.java

@@ -39,8 +39,8 @@ class RestResponseEntityExceptionHandlerUnitTest {
         final var errorResponse = exceptionHandler.handleConflict(givenException, givenWebRequest);
 
         // then
-        assertThat(errorResponse.getBody().getStatusCode()).isEqualTo(409);
-        assertThat(errorResponse.getBody().getMessage()).isEqualTo("ERROR: [409] First Line");
+        assertThat(errorResponse.getBody()).extracting(CustomErrorResponse::getStatusCode).isEqualTo(409);
+        assertThat(errorResponse.getBody()).extracting(CustomErrorResponse::getMessage).isEqualTo("ERROR: [409] First Line");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/test/LogbackLogPattern.java

@@ -0,0 +1,21 @@
+package net.hostsharing.hsadminng.test;
+
+import ch.qos.logback.classic.pattern.TargetLengthBasedClassNameAbbreviator;
+import org.springframework.boot.logging.LogLevel;
+
+public class LogbackLogPattern {
+
+    private static final int LOGBACK_MAX_CLASSNAME_LENGTH = 36;
+
+    /**
+     * @return a regular expression for a log message
+     */
+    public static CharSequence of(
+            final LogLevel logLevel,
+            final Class<?> loggingClass,
+            final String message) {
+        final var abbreviator = new TargetLengthBasedClassNameAbbreviator(LOGBACK_MAX_CLASSNAME_LENGTH);
+        final var shortenedClassName = abbreviator.abbreviate(loggingClass.getName());
+        return logLevel + " [0-9]+ .* " + shortenedClassName +  " *: " + message;
+    }
+}