Add comprehensive tests for isProperFraction function covering edge cases and various scenarios

Author: TTiamiyu

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

@@ -8,3 +8,37 @@ const isProperFraction = require("../implement/2-is-proper-fraction");
 test(`should return false when denominator is zero`, () => {
   expect(isProperFraction(1, 0)).toEqual(false);
 });
+// Special case: numerator is zero
+test("should return false when denominator is zero", () => {
+  expect(isProperFraction(1, 0)).toEqual(false);
+});
+
+// Positive proper fractions
+test("should return true for positive proper fractions", () => {
+  expect(isProperFraction(1, 2)).toEqual(true);
+  expect(isProperFraction(3, 4)).toEqual(true);
+});
+
+// Positive improper fractions
+test("should return false for positive improper fractions", () => {
+  expect(isProperFraction(5, 2)).toEqual(false);
+  expect(isProperFraction(4, 4)).toEqual(false); // equal numerator/denominator
+});
+
+// Negative numbers
+test("should handle negative numerators and denominators", () => {
+  expect(isProperFraction(-1, 2)).toEqual(true);
+  expect(isProperFraction(1, -2)).toEqual(true);
+  expect(isProperFraction(-3, -4)).toEqual(true);
+  expect(isProperFraction(-5, 2)).toEqual(false);
+});
+
+// Numerator is zero
+test("should return true when numerator is zero and denominator is non-zero", () => {
+  expect(isProperFraction(0, 5)).toEqual(true);
+});
+
+// Both zero
+test("should return false when both numerator and denominator are zero", () => {
+  expect(isProperFraction(0, 0)).toEqual(false);
+});