diff --git a/pom.xml b/pom.xml
index 4a46341f..c3b6dffb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -377,6 +377,9 @@
             <exclusions>
               <exclusion>**/docker/**</exclusion>
               <exclusion>**/AbstractComparableTest.java</exclusion>
+              <exclusion>**/AbstractEqualsTest.java</exclusion>
+              <exclusion>**/EnsureTest.java</exclusion>
+              <exclusion>**/ResourceExtractorTest.java</exclusion>
             </exclusions>
             <activeRecipes>
               <recipe>org.openrewrite.maven.BestPractices</recipe>
diff --git a/src/test/java/edu/hm/hafner/util/ACTest.java b/src/test/java/edu/hm/hafner/util/ACTest.java
new file mode 100644
index 00000000..8fedc248
--- /dev/null
+++ b/src/test/java/edu/hm/hafner/util/ACTest.java
@@ -0,0 +1,24 @@
+package edu.hm.hafner.util;
+
+public abstract class ACTest<T extends Comparable<T>> {
+    void shouldBeNegativeIfThisIsSmaller() {
+        T smaller = createSmallerSut();
+        T greater = createGreaterSut();
+    }
+
+    /**
+     * Creates a subject under test. The SUT must be smaller than the SUT of the opposite method {@link
+     * #createGreaterSut()}.
+     *
+     * @return the SUT
+     */
+    protected abstract T createSmallerSut();
+
+    /**
+     * Creates a subject under test. The SUT must be greater than the SUT of the opposite method {@link
+     * #createSmallerSut()}.
+     *
+     * @return the SUT
+     */
+    protected abstract T createGreaterSut();
+}