Amending error message for multiple arithmetic operations

Klausuren/Sd1/2023winter/Exam/src/test/java/de/hdm_stuttgart/mi/sd1/task1/B_MaxTest.java

@@ -19,13 +19,13 @@ public class B_MaxTest extends ExaminationTestDefaults {
         assertMaximum(5.1, 0.1, 5, '+');
         assertMaximum(35, 7, 0.2, '/');
         assertMaximum(-1.4,-7, 0.2, '*');
-        assertMaximum(4,2, 2, '+');
+        assertMaximum(4,2, 2, '+', '*');
     }
 
-    private static void assertMaximum(final double expected, final double first, final double second, char operation) {
+    private static void assertMaximum(final double expected, final double first, final double second, char ... operation) {
 
-        final StringBuilder errMsg = new StringBuilder("Expected maximum is " + expected + " == " + first + " " +
-                operation + " ");
+        final StringBuilder errMsg = new StringBuilder("Expected maximum is ").append(expected).append(" == ").
+                append(first).append(" ").append(join(operation)).append(" ");
 
         if (second < 0) {
             errMsg.append("(" + second + ")");
@@ -34,4 +34,16 @@ public class B_MaxTest extends ExaminationTestDefaults {
         }
         Assert.assertEquals(errMsg.toString(), expected, B_Max.getBasicCalculationMax(first, second), PRECISION);
     }
+
+    private static String join(char[] operations) {
+        if (1 == operations.length) {
+            return Character.toString(operations[0]);
+        } else {
+            StringBuilder ret = new StringBuilder("{") .append(operations[0]);
+            for (int i = 1; i < operations.length; i++) {
+                ret.append(" or ").append(operations[i]);
+            }
+            return ret.append('}').toString();
+        }
+    }
 }