From 59d762fafe5ff80322e8f5ff1595e96f723f1824 Mon Sep 17 00:00:00 2001
From: Blake Embrey <hello@blakeembrey.com>
Date: Mon, 8 Jan 2024 14:35:33 -0600
Subject: [PATCH] Fix capitalization of acronym in sentence case

---
 packages/title-case/src/index.spec.ts | 8 ++++++++
 packages/title-case/src/index.ts      | 5 ++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/packages/title-case/src/index.spec.ts b/packages/title-case/src/index.spec.ts
index d575391f..df1fe328 100644
--- a/packages/title-case/src/index.spec.ts
+++ b/packages/title-case/src/index.spec.ts
@@ -135,7 +135,15 @@ const TEST_CASES: [string, string, Options?][] = [
     "Something About _Me-Too_? And You Too.",
   ],
   ["an example. i.e. test.", "An Example. I.e. Test."],
+  ["an example, i.e. test.", "An Example, I.e. Test."],
   ['an example. "i.e. test."', 'An Example. "I.e. Test."'],
+  ["an example. i.e. test.", "An example. I.e. test.", { sentenceCase: true }],
+  ["an example, i.e. test.", "An example, i.e. test.", { sentenceCase: true }],
+  [
+    'an example. "i.e. test."',
+    'An example. "I.e. test."',
+    { sentenceCase: true },
+  ],
 ];
 
 describe("swap case", () => {
diff --git a/packages/title-case/src/index.ts b/packages/title-case/src/index.ts
index 0ac0f080..f260ba82 100644
--- a/packages/title-case/src/index.ts
+++ b/packages/title-case/src/index.ts
@@ -101,7 +101,10 @@ export function titleCase(
       // but we should uppercase first for i.e., e.g., etc.
       if (acronym) {
         const [_, prefix = "", suffix = ""] = acronym;
-        result += upperAt(token, prefix.length, locale);
+        result +=
+          sentenceCase && !isNewSentence
+            ? token
+            : upperAt(token, prefix.length, locale);
         isNewSentence = terminators.has(suffix.charAt(0));
         continue;
       }