Refactor tests following Java migration (#10733)

Refactor tests following Java migration

address comments from #10462

Co-authored-by: jean-philippe.bempel <jean-philippe.bempel@datadoghq.com>

Author: jpbempel

buildSrc/call-site-instrumentation-plugin/src/test/java/datadog/trace/plugin/csi/impl/TypeResolverPoolTest.java

@@ -11,86 +11,57 @@
 
 class TypeResolverPoolTest {
 
+  TypeResolverPool resolver = new TypeResolverPool();
+
   @Test
   void testResolvePrimitive() {
-    TypeResolverPool resolver = new TypeResolverPool();
-
-    Class<?> result = resolver.resolveType(Type.INT_TYPE);
-
-    assertEquals(int.class, result);
+    assertEquals(int.class, resolver.resolveType(Type.INT_TYPE));
   }
 
   @Test
   void testResolvePrimitiveArray() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type = Type.getType("[I");
-
-    Class<?> result = resolver.resolveType(type);
-
-    assertEquals(int[].class, result);
+    assertEquals(int[].class, resolver.resolveType(type));
   }
 
   @Test
   void testResolvePrimitiveMultidimensionalArray() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type = Type.getType("[[[I");
-
-    Class<?> result = resolver.resolveType(type);
-
-    assertEquals(int[][][].class, result);
+    assertEquals(int[][][].class, resolver.resolveType(type));
   }
 
   @Test
   void testResolveClass() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type = Type.getType(String.class);
-
-    Class<?> result = resolver.resolveType(type);
-
-    assertEquals(String.class, result);
+    assertEquals(String.class, resolver.resolveType(type));
   }
 
   @Test
   void testResolveClassArray() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type = Type.getType(String[].class);
-
-    Class<?> result = resolver.resolveType(type);
-
-    assertEquals(String[].class, result);
+    assertEquals(String[].class, resolver.resolveType(type));
   }
 
   @Test
   void testResolveClassMultidimensionalArray() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type = Type.getType(String[][][].class);
-
-    Class<?> result = resolver.resolveType(type);
-
-    assertEquals(String[][][].class, result);
+    assertEquals(String[][][].class, resolver.resolveType(type));
   }
 
   @Test
   void testTypeResolverFromMethod() {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type type =
         Type.getMethodType(
             Type.getType(String[].class), Type.getType(String.class), Type.getType(String.class));
-
-    Class<?> result = resolver.resolveType(type.getReturnType());
-
-    assertEquals(String[].class, result);
+    assertEquals(String[].class, resolver.resolveType(type.getReturnType()));
   }
 
   @Test
   void testInheritedMethods() throws Exception {
-    TypeResolverPool resolver = new TypeResolverPool();
     Type owner = Type.getType(HttpServletRequest.class);
     String name = "getParameter";
     Type descriptor = Type.getMethodType(Type.getType(String.class), Type.getType(String.class));
-
     Method result = (Method) resolver.resolveMethod(new MethodType(owner, name, descriptor));
-
     assertEquals(ServletRequest.class.getDeclaredMethod("getParameter", String.class), result);
   }
 }

buildSrc/call-site-instrumentation-plugin/src/test/java/datadog/trace/plugin/csi/impl/ext/IastExtensionTest.java

@@ -22,6 +22,7 @@
 import datadog.trace.plugin.csi.impl.assertion.CallSiteAssert;
 import datadog.trace.plugin.csi.impl.ext.tests.IastExtensionCallSite;
 import java.io.File;
+import java.io.IOException;
 import java.lang.reflect.Method;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -46,12 +47,15 @@ class IastExtensionTest extends BaseCsiPluginTest {
 
   @BeforeEach
   void setup() throws Exception {
-    targetFolder = buildDir.toPath().resolve("target");
-    Files.createDirectories(targetFolder);
-    projectFolder = buildDir.toPath().resolve("project");
-    Files.createDirectories(projectFolder);
-    srcFolder = projectFolder.resolve("src/main/java");
-    Files.createDirectories(srcFolder);
+    targetFolder = createFolder("target");
+    projectFolder = createFolder("project");
+    srcFolder = createFolder("src/main/java");
+  }
+
+  private Path createFolder(String folderName) throws IOException {
+    Path folder = buildDir.toPath().resolve(folderName);
+    Files.createDirectories(folder);
+    return folder;
   }
 
   @ParameterizedTest