fix bug in use modulo operator

Feuermagier · Apr 18, 2024 · cc2ccc3 · cc2ccc3
1 parent a3d1a74
commit cc2ccc3
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Showing 2 changed files with 50 additions and 3 deletions.
diff --git a/autograder-core/src/main/java/de/firemage/autograder/core/check/api/UseModuloOperator.java b/autograder-core/src/main/java/de/firemage/autograder/core/check/api/UseModuloOperator.java
@@ -70,17 +70,23 @@ private void checkModulo(CtIf ctIf) {
         // is equal to
         //
         // variable %= 3;
-        if (Set.of(BinaryOperatorKind.GE, BinaryOperatorKind.EQ).contains(condition.getKind())) {
-            CtExpression<?> right = condition.getRightHandOperand();
+        CtExpression<?> checkedValue = condition.getRightHandOperand();
 
+        // for boxed types, one could check if the value is null,
+        // for which the suggestion `a %= null` would not make sense
+        if (SpoonUtil.isNullLiteral(checkedValue)) {
+            return;
+        }
+
+        if (Set.of(BinaryOperatorKind.GE, BinaryOperatorKind.EQ).contains(condition.getKind())) {
             addLocalProblem(
                 ctIf,
                 new LocalizedMessage(
                     "common-reimplementation",
                     Map.of(
                         "suggestion", "%s %%= %s".formatted(
                             assignedVariable,
-                            right
+                            checkedValue
                         )
                     )
                 ),

diff --git a/...rader-core/src/test/java/de/firemage/autograder/core/check/api/TestUseModuloOperator.java b/...rader-core/src/test/java/de/firemage/autograder/core/check/api/TestUseModuloOperator.java
@@ -73,4 +73,45 @@ public static int adjust(int value, int limit) {
         }
         problems.assertExhausted();
     }
+
+    @Test
+    void testBoxedEqualsNull() throws LinterException, IOException {
+        ProblemIterator problems = this.checkIterator(StringSourceInfo.fromSourceString(
+            JavaVersion.JAVA_17,
+            "Main",
+            """
+                public class Main {
+                    public static void test(Integer i) {
+                        if (i == null) {
+                            i = 0;
+                        }
+                    }
+                }
+                """
+        ), PROBLEM_TYPES);
+
+        problems.assertExhausted();
+    }
+
+    @Test
+    void testBoxedInteger() throws LinterException, IOException {
+        ProblemIterator problems = this.checkIterator(StringSourceInfo.fromSourceString(
+            JavaVersion.JAVA_17,
+            "Main",
+            """
+                public class Main {
+                    public static void test(Integer i) {
+                        Integer j = 7;
+                        if (i == j) {
+                            i = 0;
+                        }
+                    }
+                }
+                """
+        ), PROBLEM_TYPES);
+
+        assertReimplementation(problems.next(), "i %= j");
+
+        problems.assertExhausted();
+    }
 }