Initial commit: Complete Shopify Price Updater implementation

- Full Node.js application with Shopify GraphQL API integration
- Compare At price support for promotional pricing
- Comprehensive error handling and retry logic
- Progress tracking with markdown logging
- Complete test suite with unit and integration tests
- Production-ready with proper exit codes and signal handling

test-additional-price-cases.js

@@ -0,0 +1,61 @@
+// Additional edge case tests for price utilities
+const {
+	calculateNewPrice,
+	isValidPrice,
+	formatPrice,
+	calculatePercentageChange,
+	isValidPercentage,
+} = require("./src/utils/price.js");
+
+console.log("Testing Additional Edge Cases...\n");
+
+// Test very small prices
+console.log("=== Testing Small Prices ===");
+console.log("1% increase on $0.01:", calculateNewPrice(0.01, 1)); // Should be 0.01
+console.log("50% increase on $0.02:", calculateNewPrice(0.02, 50)); // Should be 0.03
+
+// Test large prices
+console.log("\n=== Testing Large Prices ===");
+console.log("10% increase on $9999.99:", calculateNewPrice(9999.99, 10)); // Should be 10999.99
+
+// Test decimal percentages
+console.log("\n=== Testing Decimal Percentages ===");
+console.log("0.5% increase on $100:", calculateNewPrice(100, 0.5)); // Should be 100.50
+console.log("2.75% decrease on $80:", calculateNewPrice(80, -2.75)); // Should be 77.80
+
+// Test rounding edge cases
+console.log("\n=== Testing Rounding Edge Cases ===");
+console.log("33.33% increase on $3:", calculateNewPrice(3, 33.33)); // Should round properly
+console.log("Formatting 99.999:", formatPrice(99.999)); // Should be "100.00" due to rounding
+
+// Test invalid inputs
+console.log("\n=== Testing Invalid Inputs ===");
+try {
+	calculateNewPrice(null, 10);
+} catch (error) {
+	console.log("✓ Null price error:", error.message);
+}
+
+try {
+	calculateNewPrice(100, null);
+} catch (error) {
+	console.log("✓ Null percentage error:", error.message);
+}
+
+try {
+	calculateNewPrice(100, Infinity);
+} catch (error) {
+	console.log("✓ Infinity percentage handled");
+}
+
+// Test percentage change with zero
+console.log("\n=== Testing Percentage Change Edge Cases ===");
+try {
+	console.log("Change from $0 to $10:", calculatePercentageChange(0, 10)); // Should be Infinity
+} catch (error) {
+	console.log("Zero base price handled:", error.message);
+}
+
+console.log("Change from $10 to $0:", calculatePercentageChange(10, 0)); // Should be -100
+
+console.log("\n✓ Additional edge case tests completed!");