feat: test coverage for utils

src/shared/lib/utils/getDecimalPlaces/getDecimalPlaces.test.ts

@@ -0,0 +1,188 @@
+/**
+ * Tests for getDecimalPlaces utility
+ */
+
+import {
+    describe,
+    expect,
+    test,
+} from 'vitest';
+import { getDecimalPlaces } from './getDecimalPlaces';
+
+describe('getDecimalPlaces', () => {
+    describe('basic functionality', () => {
+        test('should return 0 for integers', () => {
+            expect(getDecimalPlaces(0)).toBe(0);
+            expect(getDecimalPlaces(1)).toBe(0);
+            expect(getDecimalPlaces(42)).toBe(0);
+            expect(getDecimalPlaces(-7)).toBe(0);
+            expect(getDecimalPlaces(1000)).toBe(0);
+        });
+
+        test('should return correct decimal places for decimals', () => {
+            expect(getDecimalPlaces(0.1)).toBe(1);
+            expect(getDecimalPlaces(0.5)).toBe(1);
+            expect(getDecimalPlaces(0.01)).toBe(2);
+            expect(getDecimalPlaces(0.05)).toBe(2);
+            expect(getDecimalPlaces(0.001)).toBe(3);
+            expect(getDecimalPlaces(0.123)).toBe(3);
+            expect(getDecimalPlaces(0.123456)).toBe(6);
+        });
+
+        test('should handle negative decimal numbers', () => {
+            expect(getDecimalPlaces(-0.1)).toBe(1);
+            expect(getDecimalPlaces(-0.05)).toBe(2);
+            expect(getDecimalPlaces(-1.5)).toBe(1);
+            expect(getDecimalPlaces(-99.99)).toBe(2);
+        });
+    });
+
+    describe('whole numbers with decimal part', () => {
+        test('should handle numbers with integer and decimal parts', () => {
+            expect(getDecimalPlaces(1.5)).toBe(1);
+            expect(getDecimalPlaces(10.25)).toBe(2);
+            expect(getDecimalPlaces(100.125)).toBe(3);
+            expect(getDecimalPlaces(1234.5678)).toBe(4);
+        });
+
+        test('should handle trailing zeros correctly', () => {
+            // Note: JavaScript string representation drops trailing zeros
+            expect(getDecimalPlaces(1.5)).toBe(1);
+            expect(getDecimalPlaces(1.50)).toBe(1); // 1.50 becomes "1.5" in string
+        });
+    });
+
+    describe('edge cases', () => {
+        test('should handle zero', () => {
+            expect(getDecimalPlaces(0)).toBe(0);
+            expect(getDecimalPlaces(0.0)).toBe(0);
+        });
+
+        test('should handle very small decimals', () => {
+            expect(getDecimalPlaces(0.0001)).toBe(4);
+            expect(getDecimalPlaces(0.00001)).toBe(5);
+            expect(getDecimalPlaces(0.000001)).toBe(6);
+        });
+
+        test('should handle very large numbers', () => {
+            expect(getDecimalPlaces(123456789.123)).toBe(3);
+            expect(getDecimalPlaces(999999.9999)).toBe(4);
+        });
+
+        test('should handle negative whole numbers', () => {
+            expect(getDecimalPlaces(-1)).toBe(0);
+            expect(getDecimalPlaces(-100)).toBe(0);
+            expect(getDecimalPlaces(-9999)).toBe(0);
+        });
+    });
+
+    describe('special number values', () => {
+        test('should handle Infinity', () => {
+            expect(getDecimalPlaces(Infinity)).toBe(0);
+            expect(getDecimalPlaces(-Infinity)).toBe(0);
+        });
+
+        test('should handle NaN', () => {
+            expect(getDecimalPlaces(NaN)).toBe(0);
+        });
+    });
+
+    describe('scientific notation', () => {
+        test('should handle numbers in scientific notation', () => {
+            // Very small numbers may be represented in scientific notation
+            const tiny = 1e-10;
+            const result = getDecimalPlaces(tiny);
+            // The result depends on how JS represents this as a string
+            expect(typeof result).toBe('number');
+        });
+
+        test('should handle large scientific notation numbers', () => {
+            const large = 1.23e5; // 123000
+            expect(getDecimalPlaces(large)).toBe(0);
+        });
+    });
+
+    describe('real-world scenarios', () => {
+        test('should handle currency values (2 decimal places)', () => {
+            expect(getDecimalPlaces(0.01)).toBe(2); // 1 cent
+            expect(getDecimalPlaces(0.99)).toBe(2); // 99 cents
+            // Note: JavaScript string representation drops trailing zeros
+            // 10.50 becomes "10.5" in string, so returns 1 decimal place
+            expect(getDecimalPlaces(10.50)).toBe(1); // $10.50
+            expect(getDecimalPlaces(999.99)).toBe(2); // $999.99
+        });
+
+        test('should handle measurement values', () => {
+            expect(getDecimalPlaces(12.5)).toBe(1); // 12.5 mm
+            expect(getDecimalPlaces(12.34)).toBe(2); // 12.34 cm
+            expect(getDecimalPlaces(12.345)).toBe(3); // 12.345 m
+        });
+
+        test('should handle step values for sliders', () => {
+            expect(getDecimalPlaces(0.1)).toBe(1); // Fine adjustment
+            expect(getDecimalPlaces(0.25)).toBe(2); // Quarter steps
+            expect(getDecimalPlaces(0.5)).toBe(1); // Half steps
+            expect(getDecimalPlaces(1)).toBe(0); // Whole steps
+        });
+
+        test('should handle font size increments', () => {
+            expect(getDecimalPlaces(0.5)).toBe(1); // Half point increments
+            expect(getDecimalPlaces(1)).toBe(0); // Whole point increments
+        });
+
+        test('should handle opacity values', () => {
+            expect(getDecimalPlaces(0.1)).toBe(1); // 10% increments
+            expect(getDecimalPlaces(0.05)).toBe(2); // 5% increments
+            expect(getDecimalPlaces(0.01)).toBe(2); // 1% increments
+        });
+
+        test('should handle percentage values', () => {
+            expect(getDecimalPlaces(0.5)).toBe(1); // 0.5%
+            expect(getDecimalPlaces(12.5)).toBe(1); // 12.5%
+            expect(getDecimalPlaces(33.33)).toBe(2); // 33.33%
+        });
+
+        test('should handle coordinate precision', () => {
+            expect(getDecimalPlaces(12.3456789)).toBe(7); // High precision GPS
+            expect(getDecimalPlaces(100.5)).toBe(1); // Low precision coordinates
+        });
+
+        test('should handle time values', () => {
+            expect(getDecimalPlaces(0.1)).toBe(1); // 100ms
+            expect(getDecimalPlaces(0.01)).toBe(2); // 10ms
+            expect(getDecimalPlaces(0.001)).toBe(3); // 1ms
+        });
+    });
+
+    describe('common step values', () => {
+        test('should correctly identify precision of common step values', () => {
+            expect(getDecimalPlaces(0.05)).toBe(2); // Very fine steps
+            expect(getDecimalPlaces(0.1)).toBe(1); // Fine steps
+            expect(getDecimalPlaces(0.25)).toBe(2); // Quarter steps
+            expect(getDecimalPlaces(0.5)).toBe(1); // Half steps
+            expect(getDecimalPlaces(1)).toBe(0); // Whole steps
+            expect(getDecimalPlaces(2)).toBe(0); // Even steps
+            expect(getDecimalPlaces(5)).toBe(0); // Five steps
+            expect(getDecimalPlaces(10)).toBe(0); // Ten steps
+            expect(getDecimalPlaces(25)).toBe(0); // Twenty-five steps
+            expect(getDecimalPlaces(50)).toBe(0); // Fifty steps
+            expect(getDecimalPlaces(100)).toBe(0); // Hundred steps
+        });
+    });
+
+    describe('floating-point representation', () => {
+        test('should handle standard floating-point representation', () => {
+            expect(getDecimalPlaces(1.1)).toBe(1);
+            expect(getDecimalPlaces(1.2)).toBe(1);
+            expect(getDecimalPlaces(1.3)).toBe(1);
+        });
+
+        test('should handle numbers that might have floating-point issues', () => {
+            // 0.1 + 0.2 = 0.30000000000000004 in JS
+            const sum = 0.1 + 0.2;
+            const places = getDecimalPlaces(sum);
+            // The function analyzes the string representation
+            expect(typeof places).toBe('number');
+        });
+    });
+});