LibJS: Correct behaviour of direct vs. indirect eval

eval only has direct access to the local scope when accessed through
the name eval. This includes locals named eval, because of course it
does.

1 files changed, 43 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Tests/eval-basic.js b/Userland/Libraries/LibJS/Tests/eval-basic.js
index 43b75028c6..0443d39662 100644
--- a/Userland/Libraries/LibJS/Tests/eval-basic.js
+++ b/Userland/Libraries/LibJS/Tests/eval-basic.js
@@ -30,3 +30,46 @@ test("returns 1st argument unless 1st argument is a string", () => {
     var stringObject = new String("1 + 2");
     expect(eval(stringObject)).toBe(stringObject);
 });
+
+// These eval scope tests use function expressions due to bug #8198
+var testValue = "outer";
+test("eval only touches locals if direct use", function () {
+    var testValue = "inner";
+    expect(globalThis.eval("testValue")).toEqual("outer");
+});
+
+test("alias to eval works as a global eval", function () {
+    var testValue = "inner";
+    var eval1 = globalThis.eval;
+    expect(eval1("testValue")).toEqual("outer");
+});
+
+test("eval evaluates all args", function () {
+    var i = 0;
+    expect(eval("testValue", i++, i++, i++)).toEqual("outer");
+    expect(i).toEqual(3);
+});
+
+test("eval tests for exceptions", function () {
+    var i = 0;
+    expect(function () {
+        eval("testValue", i++, i++, j, i++);
+    }).toThrowWithMessage(ReferenceError, "'j' is not defined");
+    expect(i).toEqual(2);
+});
+
+test("direct eval inherits non-strict evaluation", function () {
+    expect(eval("01")).toEqual(1);
+});
+
+test("direct eval inherits strict evaluation", function () {
+    "use strict";
+    expect(() => {
+        eval("01");
+    }).toThrowWithMessage(SyntaxError, "Unprefixed octal number not allowed in strict mode");
+});
+
+test("global eval evaluates as non-strict", function () {
+    "use strict";
+    expect(globalThis.eval("01"));
+});