Throw when case mapping result > max string length

test/intl/general/case-mapping.js

Index: test/intl/general/case-mapping.js
diff --git a/test/intl/general/case-mapping.js b/test/intl/general/case-mapping.js
index a73622bf0deb9cfdf35ae0071737bb5c633cbeb8..548f6e95b7988a7b8a4ba3df1af6866cc8b2ccfe 100644
--- a/test/intl/general/case-mapping.js
+++ b/test/intl/general/case-mapping.js
@@ -136,3 +136,38 @@ assertEquals("\u{10CC0}", "\u{10C80}".toLocaleLowerCase());
 assertEquals("\u{10C80}", "\u{10CC0}".toLocaleUpperCase(["tr"]));
 assertEquals("\u{10C80}", "\u{10CC0}".toLocaleUpperCase(["tr"]));
 assertEquals("\u{10CC0}", "\u{10C80}".toLocaleLowerCase());
+
+// If the result of case mapping is longer than the max string length
+// (1<<28 - 16), it should throw a range error instead of crashing.
+var invalidValues = [
+  { s: "\u0390", opType: 0 },
+  { s: "ß", opType: 0 },
+  { s: "\uFB01", opType: 0 }, // fi ligature
+  { s: "\uFB04", opType: 0 }, // ffl ligature
+  { s: "\u0390", opType: 1, locale: "und" },
+  { s: "\u00CC", opType: 2, locale: "lt" },
+  { s: "\u0130", opType: 2, locale: "en" },
+];
+
+invalidValues.forEach(function(value) {

[Dan Ehrenberg, 2016/08/10 19:06:23]

Wouldn't this be a great place to use destructuring? function({s, locale,
opType})... :)

+  var error;
+  try {
+    var s = value.s.repeat(1<<27);
+    switch (value.opType) {
+      case 0:
+        s.toUpperCase();
+        break;
+      case 1:
+        s.toLocaleUpperCase(value.locale);
+        break;
+      case 2:
+        s.toLocaleLowerCase(value.locale);
+        break;
+    }
+  } catch (e) {
+    error = e;
+  }
+
+  assertTrue(error !== undefined);
+  assertEquals('RangeError', error.name);

[Dan Ehrenberg, 2016/08/10 19:08:02]

You could also do assertThrows(() => s.toLocaleUpperCase(value.locale),
RangeError).

+});