Also swap assertNull and assertNotNull argument order (#440)

* Also swap assertNull and assertNotNull argument order

* Use wildcard

* Fix argument matcher

Author: timtebeek

src/main/java/org/openrewrite/java/testing/cleanup/AssertionsArgumentOrder.java

@@ -42,6 +42,9 @@ public class AssertionsArgumentOrder extends Recipe {
     };
     private static final MethodMatcher jupiterAssertIterableEqualsMatcher = new MethodMatcher("org.junit.jupiter.api.Assertions assertIterableEquals(..)");
 
+    // `assertNull("message", result())` should be `assertNull(result(), "message")`
+    private static final MethodMatcher jupiterAssertNullMatcher = new MethodMatcher("org.junit.jupiter.api.Assertions assert*Null(Object, String)");
+
     private static final MethodMatcher[] testNgMatcher = new MethodMatcher[]{
             new MethodMatcher("org.testng.Assert assertSame(..)"),
             new MethodMatcher("org.testng.Assert assertNotSame(..)"),
@@ -54,6 +57,7 @@ public class AssertionsArgumentOrder extends Recipe {
     static {
         List<MethodMatcher> matchers = new ArrayList<>(Arrays.asList(jupiterAssertionMatchers));
         matchers.add(jupiterAssertIterableEqualsMatcher);
+        matchers.add(jupiterAssertNullMatcher);
         matchers.addAll(Arrays.asList(testNgMatcher));
         //noinspection unchecked
         precondition = Preconditions.or(matchers.stream().map(UsesMethod::new).toArray(TreeVisitor[]::new));
@@ -117,6 +121,9 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
         }
 
         private boolean isCorrectOrder(Expression expected, Expression actual, J.MethodInvocation mi) {
+            if (jupiterAssertNullMatcher.matches(mi)) {
+                return isConstant(actual, mi) || !isConstant(expected, mi);
+            }
             return isConstant(expected, mi) || !isConstant(actual, mi);
         }
 
@@ -156,7 +163,7 @@ private boolean isJupiterAssertion(J.MethodInvocation mi) {
                     return true;
                 }
             }
-            return jupiterAssertIterableEqualsMatcher.matches(mi);
+            return jupiterAssertIterableEqualsMatcher.matches(mi) || jupiterAssertNullMatcher.matches(mi);
         }
 
         private boolean isTestNgAssertion(J.MethodInvocation mi) {

src/test/java/org/openrewrite/java/testing/cleanup/AssertionsArgumentOrderTest.java

@@ -25,7 +25,7 @@
 
 import static org.openrewrite.java.Assertions.java;
 
-public class AssertionsArgumentOrderTest implements RewriteTest {
+class AssertionsArgumentOrderTest implements RewriteTest {
     @Override
     public void defaults(RecipeSpec spec) {
         spec.recipe(new AssertionsArgumentOrder())
@@ -71,6 +71,47 @@ String result() {
         );
     }
 
+    @Test
+    void junitAssertNullAndAssertNotNull() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              import static org.junit.jupiter.api.Assertions.assertNotNull;
+              import static org.junit.jupiter.api.Assertions.assertNull;
+                          
+              class MyTest {
+                  void someMethod() {
+                      assertNull(result(), "message");
+                      assertNull("message", result());
+                      assertNotNull(result(), "message");
+                      assertNotNull("message", result());
+                  }
+                  String result() {
+                      return "result";
+                  }
+              }
+              """,
+            """
+              import static org.junit.jupiter.api.Assertions.assertNotNull;
+              import static org.junit.jupiter.api.Assertions.assertNull;
+                          
+              class MyTest {
+                  void someMethod() {
+                      assertNull(result(), "message");
+                      assertNull(result(), "message");
+                      assertNotNull(result(), "message");
+                      assertNotNull(result(), "message");
+                  }
+                  String result() {
+                      return "result";
+                  }
+              }
+              """
+          )
+        );
+    }
+
     @Test
     void jupiterAssertSameNotSame() {
         rewriteRun(