diff --git a/README.md b/README.md
index eb4802e7..6565d69e 100644
--- a/README.md
+++ b/README.md
@@ -81,7 +81,7 @@ You can configure the `pom.xml` file of your Maven project to use DepClean as pa
 ```
 
 Or you can run DepClean directly from the command line.
-Let's see it in action with the project https://github.com/apache/commons-numbers/tree/master/commons-numbers-examples/examples-jmh:
+Let's see it in action with the project [Apache Commons Numbers](https://github.com/apache/commons-numbers/tree/master/commons-numbers-examples/examples-jmh)!
 
 ![Demo](https://github.com/castor-software/depclean/blob/master/.img/demo.gif)
 
diff --git a/depclean-core/src/main/java/se/kth/depclean/core/analysis/ClassFileVisitorUtils.java b/depclean-core/src/main/java/se/kth/depclean/core/analysis/ClassFileVisitorUtils.java
index f4dad7ae..bd717d60 100644
--- a/depclean-core/src/main/java/se/kth/depclean/core/analysis/ClassFileVisitorUtils.java
+++ b/depclean-core/src/main/java/se/kth/depclean/core/analysis/ClassFileVisitorUtils.java
@@ -64,13 +64,13 @@ public static void accept(URL url, ClassFileVisitor visitor)
           if (file.isDirectory()) {
             acceptDirectory(file, visitor);
           } else if (file.exists()) {
-            throw new IllegalArgumentException(message + url);
+            throw new IllegalArgumentException(message + url + " because file is not a directory.");
           }
         } catch (URISyntaxException exception) {
           throw new IllegalArgumentException(message + url, exception);
         }
       } else {
-        throw new IllegalArgumentException(message + url);
+        throw new IllegalArgumentException(message + url + " because url isn't pointing a file.");
       }
     }
   }
diff --git a/depclean-core/src/main/java/se/kth/depclean/core/analysis/DefaultProjectDependencyAnalyzer.java b/depclean-core/src/main/java/se/kth/depclean/core/analysis/DefaultProjectDependencyAnalyzer.java
index a562cde5..9d3ef78b 100644
--- a/depclean-core/src/main/java/se/kth/depclean/core/analysis/DefaultProjectDependencyAnalyzer.java
+++ b/depclean-core/src/main/java/se/kth/depclean/core/analysis/DefaultProjectDependencyAnalyzer.java
@@ -75,6 +75,7 @@ public DefaultProjectDependencyAnalyzer(boolean isIgnoredTest) {
    * @throws ProjectDependencyAnalyzerException if the analysis fails.
    * @see <code>ProjectDependencyAnalyzer#analyze(org.apache.invoke.project.MavenProject)</code>
    */
+  @Override
   public ProjectDependencyAnalysis analyze(MavenProject project) throws ProjectDependencyAnalyzerException {
     try {
       // a map of [dependency] -> [classes]
diff --git a/depclean-core/src/main/java/se/kth/depclean/core/analysis/asm/DependencyClassFileVisitor.java b/depclean-core/src/main/java/se/kth/depclean/core/analysis/asm/DependencyClassFileVisitor.java
index 9a50e50f..c61ca234 100644
--- a/depclean-core/src/main/java/se/kth/depclean/core/analysis/asm/DependencyClassFileVisitor.java
+++ b/depclean-core/src/main/java/se/kth/depclean/core/analysis/asm/DependencyClassFileVisitor.java
@@ -47,6 +47,7 @@ public class DependencyClassFileVisitor implements ClassFileVisitor {
    *
    * @see org.apache.invoke.shared.dependency.analyzer.ClassFileVisitor#visitClass(java.lang.String.java.io.InputStream)
    */
+  @Override
   public void visitClass(String className, InputStream in) {
     try {
       ClassReader reader = new ClassReader(in);
diff --git a/depclean-core/src/test/java/se/kth/depclean/core/analysis/CollectorClassFileVisitorTest.java b/depclean-core/src/test/java/se/kth/depclean/core/analysis/CollectorClassFileVisitorTest.java
new file mode 100644
index 00000000..4214211c
--- /dev/null
+++ b/depclean-core/src/test/java/se/kth/depclean/core/analysis/CollectorClassFileVisitorTest.java
@@ -0,0 +1,32 @@
+package se.kth.depclean.core.analysis;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.util.HashSet;
+import java.util.Set;
+import lombok.extern.slf4j.Slf4j;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+@Slf4j
+class CollectorClassFileVisitorTest {
+
+  private static final File classFile = new File("src/test/resources/ClassFileVisitorResources/test.class");
+  private static final String className = "test";
+  private static final CollectorClassFileVisitor collector = new CollectorClassFileVisitor();
+
+  @Test
+  @DisplayName("Test that the class is visited and added to the set of visited classes")
+  void whenClassIsVisited_thenItIsAddedToTheSetOfVisitedClasses() throws FileNotFoundException {
+    FileInputStream fileInputStream = new FileInputStream(classFile);
+    try {
+      collector.visitClass(className, fileInputStream);
+    } catch (IllegalArgumentException e) {
+      log.error("Failed to visit the class at: " + classFile.getAbsolutePath());
+    }
+    Set<String> visitedClasses = new HashSet<>(collector.getClasses());
+    Assertions.assertFalse(visitedClasses.isEmpty());
+  }
+}
diff --git a/depclean-core/src/test/resources/ClassFileVisitorResources/test.class b/depclean-core/src/test/resources/ClassFileVisitorResources/test.class
new file mode 100644
index 00000000..18c6de86
Binary files /dev/null and b/depclean-core/src/test/resources/ClassFileVisitorResources/test.class differ