Clarify when format throws a RangeError and fix the test for it

marnusw · Feb 24, 2022 · 33f803f · 33f803f
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,7 +1,8 @@
 ### v1.3.0 (23 February 2022)
 
-- [ENHANCEMENT] Native ESM support via `exports` configuration in `package.json`
+- [ENHANCEMENT] Native ESM support via `exports` configuration in `package.json` (#133, #150)
 - [DOCS] Clarify the use of ESM vs CommonJS import paths
+- [DOCS] Clarify when `format` throws a `RangeError` and fix the test for it (#152)
 
 ### v1.2.2 (21 December 2021)
 
@@ -32,7 +33,7 @@
 
 ### v1.1.5 (27 July 2021)
 
-- [BUGFIX] Fixing parsing IANA strings (#129)
+- [BUGFIX] Fixed parsing IANA strings (#129)
 
 ### v1.1.4 (13 April 2021)
 

diff --git a/README.md b/README.md
@@ -213,7 +213,9 @@ zone (if provided, see below) rather than the system time zone.
 Since a JavaScript `Date` instance cannot convey the time zone information to the `format` function
 it is necessary to pass the `timeZone` value as an option on the third argument of `format`.
 
-Similar to `date-fns/format`, when an invalid date or time zone is used a `RangeError` is thrown.
+Similar to `date-fns/format`, when an invalid date is used a `RangeError` is thrown. When an invalid
+time zone is provided _and included in the output_, i.e. with time zone tokens in the format
+string, it will also throw a `RangeError`.
 
 To format a date showing time for a specific time zone other than the system time zone, the
 `format` function can be combined with `utcToZonedTime`. This is what `formatInTimeZone` does

diff --git a/src/format/test.js b/src/format/test.js
@@ -773,11 +773,10 @@ describe('format', function () {
     it('throws RangeError if the time zone is invalid and included in the output', () => {
       var result = format(new Date(2021, 11, 20), 'MMMM d, yyyy', { timeZone: 'bad/timeZone' })
       assert.equal(result, 'December 20, 2021')
-      try {
-        format(new Date(), 'MMMM d, yyyy zzz', { timeZone: 'bad/timeZone' })
-      } catch (error) {
-        assert.deepEqual(error, new Error('Invalid time zone specified: bad/timeZone'))
-      }
+      assert.throws(
+        () => format(new Date(), 'MMMM d, yyyy zzz', { timeZone: 'bad/timeZone' }),
+        /RangeError: Invalid time zone specified: bad\/timeZone$/
+      )
     })
 
     it('handles dates before 100 AD', function () {