testing: refactor to ParameterizedTest PrefixEvaluatorTest (#6415)

testing: refactor to ParameterizedTest PrefixEvaluatorTest

Co-authored-by: Deniz Altunkapan <[email protected]>

Author: alxkm

src/test/java/com/thealgorithms/stacks/PrefixEvaluatorTest.java

@@ -4,24 +4,28 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.EmptyStackException;
+import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 
 public class PrefixEvaluatorTest {
 
-    @Test
-    public void testValidExpressions() {
-        assertEquals(10, PrefixEvaluator.evaluatePrefix("+ * 2 3 4"));
-        assertEquals(5, PrefixEvaluator.evaluatePrefix("- + 7 3 5"));
-        assertEquals(6, PrefixEvaluator.evaluatePrefix("/ * 3 2 1"));
+    @ParameterizedTest(name = "Expression: \"{0}\" → Result: {1}")
+    @CsvSource({"'+ * 2 3 4', 10", "'- + 7 3 5', 5", "'/ * 3 2 1', 6"})
+    void testValidExpressions(String expression, int expected) {
+        assertEquals(expected, PrefixEvaluator.evaluatePrefix(expression));
     }
 
     @Test
-    public void testInvalidExpression() {
+    @DisplayName("Should throw EmptyStackException for incomplete expression")
+    void testInvalidExpression() {
         assertThrows(EmptyStackException.class, () -> PrefixEvaluator.evaluatePrefix("+ 3"));
     }
 
     @Test
-    public void testMoreThanOneStackSizeAfterEvaluation() {
+    @DisplayName("Should throw IllegalArgumentException if stack not reduced to one result")
+    void testMoreThanOneStackSizeAfterEvaluation() {
         assertThrows(IllegalArgumentException.class, () -> PrefixEvaluator.evaluatePrefix("+ 3 4 5"));
     }
 }