1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/substring-inline-strings.js b/js/src/jit-test/tests/basic/substring-inline-strings.js
new file mode 100644
index 0000000000..d881514923
--- /dev/null
+++ b/js/src/jit-test/tests/basic/substring-inline-strings.js
@@ -0,0 +1,49 @@
+let hasStringRepresentation = typeof stringRepresentation === "function";
+
+function testLatin1() {
+  var s = "abcdefghijklmnopqrstuvwxyz";
+  for (var i = 0; i < 100; i++) {
+    var sub8 = s.substring(0, 8);
+    assertEq(sub8, "abcdefgh");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub8).startsWith("((JSThinInlineString"), true);
+    }
+
+    var sub24 = s.substring(0, 24);
+    assertEq(sub24, "abcdefghijklmnopqrstuvwx");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub24).startsWith("((JSFatInlineString"), true);
+    }
+
+    var sub25 = s.substring(0, 25);
+    assertEq(sub25, "abcdefghijklmnopqrstuvwxy");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub25).startsWith("((JSDependentString"), true);
+    }
+  }
+}
+testLatin1();
+
+function testTwoByte() {
+  var s = "\u1000bcdefghijklmnopqrstuvwxyz";
+  for (var i = 0; i < 100; i++) {
+    var sub4 = s.substring(0, 4);
+    assertEq(sub4, "\u1000bcd");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub4).startsWith("((JSThinInlineString"), true);
+    }
+
+    var sub12 = s.substring(0, 12);
+    assertEq(sub12, "\u1000bcdefghijkl");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub12).startsWith("((JSFatInlineString"), true);
+    }
+
+    var sub13 = s.substring(0, 13);
+    assertEq(sub13, "\u1000bcdefghijklm");
+    if (hasStringRepresentation) {
+      assertEq(stringRepresentation(sub13).startsWith("((JSDependentString"), true);
+    }
+  }
+}
+testTwoByte();