Enhance Jest tests for isProperFraction function

Expanded test cases for isProperFraction function to include various scenarios such as negative fractions, zero numerator, negative denominator, and large numbers.

Author: Alaa-Tagi

Sprint-3/1-implement-and-rewrite-tests/rewrite-tests-with-jest/2-is-proper-fraction.test.js

@@ -1,26 +1,55 @@
-// This statement loads the isProperFraction function you wrote in the implement directory.
-// We will use the same function, but write tests for it using Jest in this file.
 const isProperFraction = require("../implement/2-is-proper-fraction");
 
+// Case 1: Proper fraction
+// When numerator < denominator, it should return true.
 test("should return true for a proper fraction", () => {
   expect(isProperFraction(2, 3)).toEqual(true);
-  
 });
 
-// Case 2: Identify Improper Fractions:
+// Case 2: Improper fraction
+// When numerator > denominator, it should return false.
 test("should return false for an improper fraction", () => {
   expect(isProperFraction(5, 2)).toEqual(false);
 });
 
-// Case 3: Identify Negative Fractions:
-test("should return false for a negative fraction", () => {
+// Case 3: Negative proper fraction
+// When numerator is negative but |numerator| < |denominator|, it should return true.
+test("should return true for a negative proper fraction", () => {
   expect(isProperFraction(-1, 2)).toEqual(true);
 });
 
-// Case 4: Identify Equal Numerator and Denominator:
+// Case 4: Equal numerator and denominator
+// When numerator === denominator, it should return false.
 test("should return false for equal numerator and denominator", () => {
   expect(isProperFraction(3, 3)).toEqual(false);
-  expect(isProperFraction(-3, 3)).toEqual(false);
-  expect(isProperFraction(3, -3)).toEqual(false);
-  expect(isProperFraction(-3, -3)).toEqual(false);
+});
+
+// Case 5: Zero numerator
+// 0 divided by any non-zero denominator is a proper fraction.
+test("should return true for zero numerator", () => {
+  expect(isProperFraction(0, 5)).toEqual(true);
+});
+
+// Case 6: Negative denominator
+// When denominator is negative, the fraction is still valid, so check absolute values.
+test("should return true when denominator is negative but |numerator| < |denominator|", () => {
+  expect(isProperFraction(2, -3)).toEqual(true);
+});
+
+// Case 7: Denominator is zero
+// Division by zero is undefined, should return false.
+test("should return false when denominator is zero", () => {
+  expect(isProperFraction(3, 0)).toEqual(false);
+});
+
+// Case 8: Both numerator and denominator are negative but |numerator| < |denominator|
+// Negative/negative cancels out, still a proper fraction.
+test("should return true when both numerator and denominator are negative and |numerator| < |denominator|", () => {
+  expect(isProperFraction(-3, -7)).toEqual(true);
+});
+
+// Case 9: Large numbers
+// It should handle large numbers correctly.
+test("should return true for large proper fractions", () => {
+  expect(isProperFraction(999, 1000)).toEqual(true);
 });