Serialize decimals that round to a whole number with a fractional digit

changelog.md

@@ -4,6 +4,9 @@ ChangeLog
 2.1.1 (????-??-??)
 ------------------
 
+* Decimals that round to a whole number, such as `1.0001`, now serialize as
+  `1.0` instead of `1.`, which is invalid and was rejected by the parser.
+  (@gyanu2507)
 * Fix: serialization of displaystring that encodes to byte values under 0xf,
   they were missing the 0 padding of %0?.
 

src/serializer.ts

@@ -129,7 +129,8 @@ export function serializeDecimal(input: number): string {
   if (signifantDigits > 12) {
     throw new SerializeError('Fractional numbers are not allowed to have more than 12 significant digits before the decimal point');
   }
-  return out;
+  // A decimal must have at least one fractional digit.
+  return out.endsWith('.') ? out + '0' : out;
 }
 
 export function serializeString(input: string): string {

test/serializer-tests.js

@@ -101,6 +101,16 @@ describe('serializer shorthands', () => {
 
   describe('serializeItem', () => {
 
+    it('should keep a fractional digit when a decimal rounds to a whole number', () => {
+
+      for (const [input, expected] of [[1.0001, '1.0'], [9.9999, '10.0'], [-0.0001, '-0.0']]) {
+        const str = serializeItem(input);
+        assert.equal(str, expected);
+        assert.deepEqual(parseItem(str), [Number(expected), new Map()]);
+      }
+
+    });
+
     it('should error when passing a type that\'s not recognized', () => {
 
       let caught = false;