Add unit tests for number formatting utilities

src/utils/__tests__/numberFormat.utils.test.ts

@@ -0,0 +1,215 @@
+import { describe, it, expect } from 'vitest';
+import {
+	formatNumber,
+	formatCompactNumber,
+	formatFollowerCount,
+	formatPercent,
+} from '../numberFormat.utils';
+
+// ---------------------------------------------------------------------------
+// Feature: Compact number formatting for supply values
+// Validates: Acceptance Criteria 1, 2, 3
+// ---------------------------------------------------------------------------
+describe('formatCompactNumber: Supply Value Formatting', () => {
+	describe('Large supply values are abbreviated', () => {
+		it('formats 1,200 as "1.2K"', () => {
+			expect(formatCompactNumber(1200)).toBe('1.2K');
+		});
+
+		it('formats 4,500 as "4.5K"', () => {
+			expect(formatCompactNumber(4500)).toBe('4.5K');
+		});
+
+		it('formats 1,000,000 as "1M"', () => {
+			expect(formatCompactNumber(1000000)).toBe('1M');
+		});
+
+		it('formats 4,500,000 as "4.5M"', () => {
+			expect(formatCompactNumber(4500000)).toBe('4.5M');
+		});
+
+		it('formats 1,200,000,000 as "1.2B"', () => {
+			expect(formatCompactNumber(1200000000)).toBe('1.2B');
+		});
+	});
+
+	describe('Small supply values display as-is', () => {
+		it('formats 0 as "0"', () => {
+			expect(formatCompactNumber(0)).toBe('0');
+		});
+
+		it('formats 1 as "1"', () => {
+			expect(formatCompactNumber(1)).toBe('1');
+		});
+
+		it('formats 999 as "999"', () => {
+			expect(formatCompactNumber(999)).toBe('999');
+		});
+
+		it('formats 500 as "500"', () => {
+			expect(formatCompactNumber(500)).toBe('500');
+		});
+	});
+
+	describe('Edge cases and missing data', () => {
+		it('returns "—" for null', () => {
+			expect(formatCompactNumber(null)).toBe('—');
+		});
+
+		it('returns "—" for undefined', () => {
+			expect(formatCompactNumber(undefined)).toBe('—');
+		});
+
+		it('returns "—" for NaN', () => {
+			expect(formatCompactNumber(NaN)).toBe('—');
+		});
+
+		it('returns "—" for Infinity', () => {
+			expect(formatCompactNumber(Infinity)).toBe('—');
+		});
+
+		it('returns "—" for negative Infinity', () => {
+			expect(formatCompactNumber(-Infinity)).toBe('—');
+		});
+	});
+});
+
+// ---------------------------------------------------------------------------
+// Feature: Full number formatting with tooltip values
+// Validates: Acceptance Criteria 2 (full value accessible via tooltip)
+// ---------------------------------------------------------------------------
+describe('formatNumber: Full Value Display for Tooltips', () => {
+	it('formats 1,200 as "1,200" in full style', () => {
+		expect(formatNumber(1200, { style: 'full' })).toBe('1,200');
+	});
+
+	it('formats 4,500,000 as "4,500,000" in full style', () => {
+		expect(formatNumber(4500000, { style: 'full' })).toBe('4,500,000');
+	});
+
+	it('default style is full, returns "1,200"', () => {
+		expect(formatNumber(1200)).toBe('1,200');
+	});
+
+	it('returns "—" for null', () => {
+		expect(formatNumber(null)).toBe('—');
+	});
+
+	it('returns "—" for undefined', () => {
+		expect(formatNumber(undefined)).toBe('—');
+	});
+
+	it('handles negative numbers: -1200 → "-1,200"', () => {
+		expect(formatNumber(-1200)).toBe('-1,200');
+	});
+});
+
+// ---------------------------------------------------------------------------
+// Feature: Configurable fraction digits
+// Validates: Precision control for different use cases
+// ---------------------------------------------------------------------------
+describe('formatCompactNumber: Configurable precision', () => {
+	it('respects maximumFractionDigits option', () => {
+		expect(formatCompactNumber(1234, { maximumFractionDigits: 0 })).toBe('1K');
+		expect(formatCompactNumber(1234, { maximumFractionDigits: 2 })).toBe('1.23K');
+	});
+
+	it('respects minimumFractionDigits option', () => {
+		expect(formatCompactNumber(1000000, { minimumFractionDigits: 2 })).toBe('1.00M');
+	});
+});
+
+// ---------------------------------------------------------------------------
+// Feature: Follower count formatting (legacy helper)
+// Validates: Backward compatibility
+// ---------------------------------------------------------------------------
+describe('formatFollowerCount: Legacy follower abbreviation', () => {
+	it('formats 1,200 as "1.2K"', () => {
+		expect(formatFollowerCount(1200)).toBe('1.2K');
+	});
+
+	it('formats 1,000,000 as "1M"', () => {
+		expect(formatFollowerCount(1000000)).toBe('1M');
+	});
+
+	it('formats 999 as "999"', () => {
+		expect(formatFollowerCount(999)).toBe('999');
+	});
+
+	it('formats 0 as "0"', () => {
+		expect(formatFollowerCount(0)).toBe('0');
+	});
+
+	it('removes ".0" suffix: 1,000 → "1K" not "1.0K"', () => {
+		expect(formatFollowerCount(1000)).toBe('1K');
+	});
+});
+
+// ---------------------------------------------------------------------------
+// Feature: Percentage formatting
+// Validates: Acceptance Criteria for badge display
+// ---------------------------------------------------------------------------
+describe('formatPercent: Percentage badge formatting', () => {
+	it('formats 12.5 as "12.5%"', () => {
+		expect(formatPercent(12.5)).toBe('12.5%');
+	});
+
+	it('formats positive value with sign option: +12.5%', () => {
+		expect(formatPercent(12.5, { signed: true })).toBe('+12.5%');
+	});
+
+	it('formats negative value with sign option: -12.5%', () => {
+		expect(formatPercent(-12.5, { signed: true })).toBe('-12.5%');
+	});
+
+	it('returns "—" for null', () => {
+		expect(formatPercent(null)).toBe('—');
+	});
+
+	it('returns "—" for undefined', () => {
+		expect(formatPercent(undefined)).toBe('—');
+	});
+
+	it('returns custom placeholder when provided', () => {
+		expect(formatPercent(null, { emptyPlaceholder: 'N/A' })).toBe('N/A');
+	});
+
+	it('respects precision options', () => {
+		expect(formatPercent(12.567, { maximumFractionDigits: 1 })).toBe('12.6%');
+	});
+});
+
+// ---------------------------------------------------------------------------
+// Integration: Verify compact display + full tooltip pattern
+// Validates: Complete acceptance criteria
+// ---------------------------------------------------------------------------
+describe('Integration: Compact display with full tooltip pattern', () => {
+	it('compact format (1.2K) + full format (1,200) enables tooltip workflow', () => {
+		const supply = 1200;
+		const displayValue = formatCompactNumber(supply);
+		const tooltipValue = formatNumber(supply);
+
+		expect(displayValue).toBe('1.2K');
+		expect(tooltipValue).toBe('1,200');
+		// Both are present and different — enables title attribute pattern
+		expect(displayValue).not.toBe(tooltipValue);
+	});
+
+	it('large supply (4.5M compact, 4,500,000 full)', () => {
+		const supply = 4500000;
+		const displayValue = formatCompactNumber(supply);
+		const tooltipValue = formatNumber(supply);
+
+		expect(displayValue).toBe('4.5M');
+		expect(tooltipValue).toBe('4,500,000');
+	});
+
+	it('small supply stays the same for both (reduces noise)', () => {
+		const supply = 42;
+		const displayValue = formatCompactNumber(supply);
+		const tooltipValue = formatNumber(supply);
+
+		expect(displayValue).toBe('42');
+		expect(tooltipValue).toBe('42');
+	});
+});