From d6b6da1a8314bb8758021074e7db45669c8dfa4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Minh=20Nguy=E1=BB=85n?= <mxn@1ec5.org>
Date: Sat, 10 Aug 2024 01:59:22 -0700
Subject: [PATCH] Fixed logic for upgrading nonexistent filter to expression

---
 index.js       | 2 +-
 index.spec.mjs | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index f673d2f..5be55da 100644
--- a/index.js
+++ b/index.js
@@ -137,7 +137,7 @@ function decimalYearFromDate(date) {
  *	that require the feature to overlap with the date range.
  */
 function constrainFilterByDateRange(filter, dateRange) {
-  if (typeof filter !== 'undefined' || isLegacyFilter(filter)) {
+  if (typeof filter !== 'undefined' && isLegacyFilter(filter)) {
     return constrainLegacyFilterByDateRange(filter, dateRange);
   } else {
     return constrainExpressionFilterByDateRange(filter, dateRange);
diff --git a/index.spec.mjs b/index.spec.mjs
index 05ea65e..9acff16 100644
--- a/index.spec.mjs
+++ b/index.spec.mjs
@@ -6,6 +6,7 @@ import {
   dateRangeFromISODate,
   decimalYearFromDate,
   dateRangeFromDate,
+  constrainFilterByDateRange,
   constrainLegacyFilterByDateRange,
   constrainExpressionFilterByDateRange,
   isLegacyFilter,
@@ -172,6 +173,14 @@ describe('isLegacyFilter', () => {
   });
 });
 
+describe('constrainFilterByDateRange', () => {
+  it('should upgrade nonexistent filter to expression-based filter', () => {
+    let upgraded = constrainFilterByDateRange(undefined, { startDecimalYear: 2013 });
+    assert.equal(upgraded.length, 10);
+    assert.equal(upgraded[0], 'let');
+  });
+});
+
 describe('constrainLegacyFilterByDateRange', () => {
   it('should upgrade top-level non-combining filter', () => {
     let original = ['in', 'class', 'primary', 'secondary', 'tertiary'];