diff --git a/src/test/java/org/gridsuite/modification/server/utils/ModificationCreation.java b/src/test/java/org/gridsuite/modification/server/utils/ModificationCreation.java
index a4921ffb9..274a7edd7 100644
--- a/src/test/java/org/gridsuite/modification/server/utils/ModificationCreation.java
+++ b/src/test/java/org/gridsuite/modification/server/utils/ModificationCreation.java
@@ -10,18 +10,21 @@
 import com.powsybl.iidm.network.EnergySource;
 import com.powsybl.iidm.network.SwitchKind;
 import com.powsybl.iidm.network.extensions.ConnectablePosition;
-import org.gridsuite.modification.server.dto.*;
+import lombok.experimental.UtilityClass;
+import org.gridsuite.modification.server.dto.CouplingDeviceInfos;
+import org.gridsuite.modification.server.dto.GeneratorCreationInfos;
+import org.gridsuite.modification.server.dto.ReactiveCapabilityCurveCreationInfos;
+import org.gridsuite.modification.server.dto.VoltageLevelCreationInfos;
+
 import java.util.Arrays;
+import java.util.List;
 
 /**
  * @author Slimane Amar <slimane.amar at rte-france.com>
  */
-public final class ModificationCreation {
-
-    private ModificationCreation() {
-    }
-
-    public static VoltageLevelCreationInfos getCreationVoltageLevel(String substationId, String voltageLevelId, String voltageLevelName) {
+@UtilityClass
+public class ModificationCreation {
+    public VoltageLevelCreationInfos getCreationVoltageLevel(String substationId, String voltageLevelId, String voltageLevelName) {
         return VoltageLevelCreationInfos.builder()
             .equipmentId(voltageLevelId)
             .equipmentName(voltageLevelName)
@@ -37,8 +40,8 @@ public static VoltageLevelCreationInfos getCreationVoltageLevel(String substatio
             .couplingDevices(Arrays.asList(CouplingDeviceInfos.builder().busbarSectionId1("1A").busbarSectionId2("1B").build())).build();
     }
 
-    public static GeneratorCreationInfos getCreationGenerator(String vlId, String generatorId, String generatorName, String busOrBusbarSectionId,
-                                                              String regulatingTerminalId, String regulatingTerminalType, String regulatingTerminalVlId) {
+    public GeneratorCreationInfos getCreationGenerator(String vlId, String generatorId, String generatorName, String busOrBusbarSectionId,
+                                                       String regulatingTerminalId, String regulatingTerminalType, String regulatingTerminalVlId) {
         return GeneratorCreationInfos.builder()
             .equipmentId(generatorId)
             .equipmentName(generatorName)
diff --git a/src/test/java/org/gridsuite/modification/server/utils/NetworkCreation.java b/src/test/java/org/gridsuite/modification/server/utils/NetworkCreation.java
index 769d9e89e..3adcbc0ba 100644
--- a/src/test/java/org/gridsuite/modification/server/utils/NetworkCreation.java
+++ b/src/test/java/org/gridsuite/modification/server/utils/NetworkCreation.java
@@ -10,22 +10,21 @@
 import com.powsybl.iidm.network.*;
 import com.powsybl.iidm.network.extensions.ConnectablePosition;
 import com.powsybl.network.store.iidm.impl.NetworkFactoryImpl;
+import lombok.experimental.UtilityClass;
 
 import java.util.UUID;
 
 import static org.gridsuite.modification.server.utils.NetworkUtil.*;
 
-public final class NetworkCreation {
-    public static final String VARIANT_ID = "variant_1";
+@UtilityClass
+public  class NetworkCreation {
+    public final String VARIANT_ID = "variant_1";
 
-    private NetworkCreation() {
-    }
-
-    public static Network create(UUID uuid, boolean createHvdcLine) {
+    public Network create(UUID uuid, boolean createHvdcLine) {
         return create(uuid, createHvdcLine, new NetworkFactoryImpl());
     }
 
-    public static Network create(UUID uuid, boolean createHvdcLine, NetworkFactory networkFactory) {
+    public Network create(UUID uuid, boolean createHvdcLine, NetworkFactory networkFactory) {
         Network network = networkFactory.createNetwork(uuid.toString(), "test");
 
         Substation s1 = createSubstation(network, "s1", "s1", Country.FR);
@@ -235,7 +234,7 @@ public static Network create(UUID uuid, boolean createHvdcLine, NetworkFactory n
         return network;
     }
 
-    public static Network createBusBreaker(UUID uuid) {
+    public Network createBusBreaker(UUID uuid) {
         Network network = new NetworkFactoryImpl().createNetwork(uuid.toString(), "test");
 
         Substation s1 = createSubstation(network, "s1", "s1", Country.FR);
@@ -250,7 +249,7 @@ public static Network createBusBreaker(UUID uuid) {
         return network;
     }
 
-    public static Network createMixedTopology(UUID uuid) {
+    public Network createMixedTopology(UUID uuid) {
         Network network = new NetworkFactoryImpl().createNetwork(uuid.toString(), "test");
 
         Substation s1 = createSubstation(network, "s1", "s1", Country.FR);
@@ -270,6 +269,7 @@ public static Network createMixedTopology(UUID uuid) {
     }
 
     /**
+     * <pre>
      *     VL1            VL2            VL3
      *
      *     ld1            g2              ld3
@@ -280,8 +280,9 @@ public static Network createMixedTopology(UUID uuid) {
      *      |              |               |
      *     bbs1 ----------bbs2------------bbs3
      *            l1             l2
+     *  </pre>
      */
-    public static Network createForDeleteVoltageLevelOnLine(UUID uuid) {
+    public Network createForDeleteVoltageLevelOnLine(UUID uuid) {
         Network network = new NetworkFactoryImpl().createNetwork(uuid.toString(), "NetworkForDeleteVoltageLevelOnLine");
 
         // VL1
diff --git a/src/test/java/org/gridsuite/modification/server/utils/NetworkWithTeePoint.java b/src/test/java/org/gridsuite/modification/server/utils/NetworkWithTeePoint.java
index a86008f1f..29c8319cb 100644
--- a/src/test/java/org/gridsuite/modification/server/utils/NetworkWithTeePoint.java
+++ b/src/test/java/org/gridsuite/modification/server/utils/NetworkWithTeePoint.java
@@ -7,9 +7,16 @@
 
 package org.gridsuite.modification.server.utils;
 
-import com.powsybl.iidm.network.*;
+import com.powsybl.iidm.network.Country;
+import com.powsybl.iidm.network.Network;
+import com.powsybl.iidm.network.NetworkFactory;
+import com.powsybl.iidm.network.Substation;
+import com.powsybl.iidm.network.SwitchKind;
+import com.powsybl.iidm.network.TopologyKind;
+import com.powsybl.iidm.network.VoltageLevel;
 import com.powsybl.iidm.network.extensions.ConnectablePosition;
 import com.powsybl.network.store.iidm.impl.NetworkFactoryImpl;
+import lombok.experimental.UtilityClass;
 
 import java.util.UUID;
 
@@ -19,16 +26,14 @@
  *
  * @author Geoffroy Jamgotchian <geoffroy.jamgotchian at rte-france.com>
  */
-public final class NetworkWithTeePoint {
-
-    private NetworkWithTeePoint() {
-    }
-
-    public static Network create(UUID uuid) {
+@UtilityClass
+public class NetworkWithTeePoint {
+    public Network create(UUID uuid) {
         return create(uuid, new NetworkFactoryImpl());
     }
 
     /**
+     * <pre>
      *     VL1            VL2            VL3
      *
      *     ld1            g2              ld3
@@ -48,9 +53,10 @@ public static Network create(UUID uuid) {
      *                    br4
      *                    |
      *                    ld4
+     * </pre>
      */
 
-    public static Network create(UUID uuid, NetworkFactory networkFactory) {
+    public Network create(UUID uuid, NetworkFactory networkFactory) {
         Network network = networkFactory.createNetwork(uuid.toString(), "NetworkWithTeePoint");
 
         // VL1
diff --git a/src/test/java/org/gridsuite/modification/server/utils/WireMockUtils.java b/src/test/java/org/gridsuite/modification/server/utils/WireMockUtils.java
index f57643473..859a48477 100644
--- a/src/test/java/org/gridsuite/modification/server/utils/WireMockUtils.java
+++ b/src/test/java/org/gridsuite/modification/server/utils/WireMockUtils.java
@@ -12,21 +12,18 @@
 import com.github.tomakehurst.wiremock.matching.RequestPatternBuilder;
 import com.github.tomakehurst.wiremock.matching.StringValuePattern;
 import com.github.tomakehurst.wiremock.stubbing.ServeEvent;
+import lombok.Data;
 
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
 
-import static org.junit.Assert.assertEquals;
+import static org.assertj.core.api.Assertions.assertThat;
 
+@Data
 public class WireMockUtils {
-
     private final WireMockServer wireMockServer;
 
-    public WireMockUtils(WireMockServer wireMockServer) {
-        this.wireMockServer = wireMockServer;
-    }
-
     public void verifyGetRequest(UUID stubId, String urlPath, Map<String, StringValuePattern> queryParams, boolean regexMatching) {
         RequestPatternBuilder requestBuilder = regexMatching ? WireMock.getRequestedFor(WireMock.urlPathMatching(urlPath)) : WireMock.getRequestedFor(WireMock.urlPathEqualTo(urlPath));
         queryParams.forEach(requestBuilder::withQueryParam);
@@ -36,7 +33,7 @@ public void verifyGetRequest(UUID stubId, String urlPath, Map<String, StringValu
 
     private void removeRequestForStub(UUID stubId, int nbRequests) {
         List<ServeEvent> serveEvents = wireMockServer.getServeEvents(ServeEventQuery.forStubMapping(stubId)).getServeEvents();
-        assertEquals(nbRequests, serveEvents.size());
+        assertThat(serveEvents).hasSize(nbRequests);
         for (ServeEvent serveEvent : serveEvents) {
             wireMockServer.removeServeEvent(serveEvent.getId());
         }