Added logic to handle static fields.

src/main/java/io/github/glytching/junit/extension/random/RandomBeansExtension.java

@@ -20,7 +20,9 @@
 import io.github.benas.randombeans.api.EnhancedRandom;
 import org.junit.jupiter.api.extension.*;
 
+import java.io.File;
 import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
@@ -205,7 +207,8 @@ public Object resolveParameter(
   }
 
   /**
-   * Inject random values into any fields which are annotated with {@link Random}
+   * Inject random values into any fields which are annotated with {@link Random}. 
+   * This method doesn't populate static fields if they have values.
    *
    * @param testInstance the instance to post-process
    * @param extensionContext the current extension context
@@ -218,9 +221,11 @@ public void postProcessTestInstance(Object testInstance, ExtensionContext extens
       if (isAnnotated(field, Random.class)) {
         Random annotation = field.getAnnotation(Random.class);
         Object randomObject = resolve(field.getType(), annotation);
-
+        
         field.setAccessible(true);
-        field.set(testInstance, randomObject);
+        if (!Modifier.isStatic(field.getModifiers()) || field.get(testInstance) == null) {
+          field.set(testInstance, randomObject);
+        }
       }
     }
   }
@@ -249,4 +254,5 @@ private Object resolve(Class<?> targetType, Random annotation) {
       return random.nextObject(targetType, annotation.excludes());
     }
   }
+
 }

src/test/java/io/github/glytching/junit/extension/random/RandomBeansExtensionFieldTest.java

@@ -34,6 +34,12 @@
 @ExtendWith(RandomBeansExtension.class)
 public class RandomBeansExtensionFieldTest {
 
+  @Random private static String anyStaticString;
+
+  // gather the random values to facilitate assertions on the not distinct-ness of the value supplied to
+  // each test
+  private static Collection<String> staticStringCollection = new HashSet<>();
+
   // gather the random values to facilitate assertions on the distinct-ness of the value supplied to
   // each test
   private final Set<String> anyStrings = new HashSet<>();
@@ -80,6 +86,11 @@ public void canInjectAFullyPopulatedRandomObject() {
     assertThatDomainObjectIsFullyPopulated(fullyPopulatedDomainObject);
   }
 
+  @Test
+  public void acnInjectStaticFields() {
+    assertThat(anyStaticString, is(notNullValue()));
+  }
+
   @Test
   public void canInjectAPartiallyPopulatedRandomObject() {
     assertThatDomainObjectIsPartiallyPopulated(partiallyPopulatedDomainObject);
@@ -148,4 +159,11 @@ public void willInjectANewRandomValueEachTime() {
       anyStrings.add(anyString);
     }
   }
+
+  @RepeatedTest(5)
+  public void willNotInjectANewRandomValueEachTime() {
+    assertThat(anyStaticString, notNullValue());
+    staticStringCollection.add(anyStaticString);
+    assertThat(staticStringCollection, is(hasSize(1)));
+  }
 }