Support Long results returned as valueString in FHIR R4

CQL Long expected values (e.g. 100L) parse to BigInt, but FHIR R4 has
no integer64 type, so servers return Long results as valueString. The
result comparison had no bigint handling, so many
CqlArithmeticFunctionsTest tests failed despite correct server output.

Compare an expected BigInt numerically against string, integer, and
bigint actuals, rejecting non-integer strings so empty or malformed
values don't match.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M6fK2KhnNsn28SJfe83Htw

Author: claude

src/shared/results-utils.ts

@@ -1,3 +1,25 @@
+/**
+ * Compares an expected CQL Long (parsed to a BigInt by cvl) against the actual value.
+ * FHIR R4 has no integer64 type, so servers return Long results as valueString
+ * (or valueInteger when the value fits), and the extracted actual is a string or number.
+ */
+function longEquals(expected: bigint, actual: any): boolean {
+	if (typeof actual === 'bigint') {
+		return expected === actual;
+	}
+	if (typeof actual === 'string') {
+		// BigInt('') is 0n and BigInt trims whitespace, so require an integer literal.
+		if (!/^[+-]?\d+$/.test(actual)) {
+			return false;
+		}
+		return BigInt(actual) === expected;
+	}
+	if (typeof actual === 'number' && Number.isInteger(actual)) {
+		return BigInt(actual) === expected;
+	}
+	return false;
+}
+
 /**
  * Compares two results for equality, handling nested objects and numbers
  */
@@ -14,6 +36,10 @@ export function resultsEqual(expected: any, actual: any): boolean {
 		return Math.abs(actual - expected) < 0.00000001;
 	}
 
+	if (typeof expected === 'bigint') {
+		return longEquals(expected, actual);
+	}
+
 	if (expected === actual) {
 		return true;
 	}

test/results-utils.test.ts

@@ -17,3 +17,33 @@ test('equal lists (order-insensitive)', () => {
 test('nested structures compared key-wise', () => {
 	expect(resultsEqual({ x: 1 }, { x: 1 })).toBe(true);
 });
+
+test('expected Long matches FHIR R4 valueString encoding', () => {
+	expect(resultsEqual(1n, '1')).toBe(true);
+	expect(resultsEqual(-1n, '-1')).toBe(true);
+	expect(resultsEqual(0n, '0')).toBe(true);
+	expect(resultsEqual(9223372036854775807n, '9223372036854775807')).toBe(true);
+	expect(resultsEqual(1n, '2')).toBe(false);
+});
+
+test('expected Long matches integer and bigint actuals', () => {
+	expect(resultsEqual(1n, 1)).toBe(true);
+	expect(resultsEqual(1n, 1n)).toBe(true);
+	expect(resultsEqual(1n, 2)).toBe(false);
+	expect(resultsEqual(1n, 1.5)).toBe(false);
+});
+
+test('expected Long rejects non-integer strings', () => {
+	expect(resultsEqual(1n, 'abc')).toBe(false);
+	expect(resultsEqual(1n, '1.5')).toBe(false);
+	expect(resultsEqual(0n, '')).toBe(false);
+	expect(resultsEqual(0n, ' 0 ')).toBe(false);
+	expect(resultsEqual(1n, null)).toBe(false);
+	expect(resultsEqual(1n, undefined)).toBe(false);
+});
+
+test('Long values compare inside lists and structures', () => {
+	expect(resultsEqual([1n, 2n], ['1', '2'])).toBe(true);
+	expect(resultsEqual({ x: 1n }, { x: '1' })).toBe(true);
+	expect(resultsEqual([1n, 2n], ['1', '3'])).toBe(false);
+});