From ed970751efe96e47540b645192f5ad46e16d6670 Mon Sep 17 00:00:00 2001
From: Frank Tang <ftang@chromium.org>
Date: Mon, 8 Jan 2024 18:48:59 -0800
Subject: [PATCH] ICU-22520 Add test case for oss-fuzz issue #65635.

---
 icu4c/source/test/intltest/dtfmttst.cpp | 12 ++++++++++++
 icu4c/source/test/intltest/dtfmttst.h   |  1 +
 2 files changed, 13 insertions(+)

diff --git a/icu4c/source/test/intltest/dtfmttst.cpp b/icu4c/source/test/intltest/dtfmttst.cpp
index 681e5d65497..037edd0002d 100644
--- a/icu4c/source/test/intltest/dtfmttst.cpp
+++ b/icu4c/source/test/intltest/dtfmttst.cpp
@@ -136,6 +136,7 @@ void DateFormatTest::runIndexedTest( int32_t index, UBool exec, const char* &nam
     TESTCASE_AUTO(TestHourCycle);
     TESTCASE_AUTO(TestHCInLocale);
     TESTCASE_AUTO(TestBogusLocale);
+    TESTCASE_AUTO(TestLongLocale);
 
     TESTCASE_AUTO_END;
 }
@@ -5885,6 +5886,17 @@ void DateFormatTest::TestBogusLocale() {
                     Locale("notalanguage")));
 }
 
+void DateFormatTest::TestLongLocale() {
+    IcuTestErrorCode status(*this, "TestLongLocale");
+    LocalPointer<DateFormat> df;
+
+    // This should not cause a crash
+    std::string s(1023, ' ');
+    s[1] = '-';
+    df.adoptInstead(DateFormat::createDateTimeInstance(DateFormat::kDateTime, DateFormat::kMedium,
+                    Locale(s.c_str())));
+}
+
 void DateFormatTest::TestHCInLocale() {
     IcuTestErrorCode status(*this, "TestHCInLocale");
     LocalPointer<Calendar> midnight(Calendar::createInstance(status));
diff --git a/icu4c/source/test/intltest/dtfmttst.h b/icu4c/source/test/intltest/dtfmttst.h
index 4c44929b27c..d967f4004e2 100644
--- a/icu4c/source/test/intltest/dtfmttst.h
+++ b/icu4c/source/test/intltest/dtfmttst.h
@@ -271,6 +271,7 @@ public:
     void TestHourCycle();
     void TestHCInLocale();
     void TestBogusLocale();
+    void TestLongLocale();
 
 private:
     UBool showParse(DateFormat &format, const UnicodeString &formattedString);