Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

38 files changed, 1220 insertions, 0 deletions

diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A1.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A1.js
new file mode 100644
index 0000000000..b304c8f2ff
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A1.js
@@ -0,0 +1,62 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: |
+    White Space and Line Terminator between RelationalExpression and "in" and
+    between "in" and ShiftExpression are allowed
+es5id: 11.8.7_A1
+description: Checking by using eval
+---*/
+
+//CHECK#1
+if (eval("'MAX_VALUE'\u0009in\u0009Number") !== true) {
+  throw new Test262Error('#1: "MAX_VALUE"\\u0009in\\u0009Number === true');
+}
+
+//CHECK#2
+if (eval("'MAX_VALUE'\u000Bin\u000BNumber") !== true) {
+  throw new Test262Error('#2: "MAX_VALUE"\\u000Bin\\u000BNumber === true');  
+}
+
+//CHECK#3
+if (eval("'MAX_VALUE'\u000Cin\u000CNumber") !== true) {
+  throw new Test262Error('#3: "MAX_VALUE"\\u000Cin\\u000CNumber === true');
+}
+
+//CHECK#4
+if (eval("'MAX_VALUE'\u0020in\u0020Number") !== true) {
+  throw new Test262Error('#4: "MAX_VALUE"\\u0020in\\u0020Number === true');
+}
+
+//CHECK#5
+if (eval("'MAX_VALUE'\u00A0in\u00A0Number") !== true) {
+  throw new Test262Error('#5: "MAX_VALUE"\\u00A0in\\u00A0Number === true');
+}
+
+//CHECK#6
+if (eval("'MAX_VALUE'\u000Ain\u000ANumber") !== true) {
+  throw new Test262Error('#6: "MAX_VALUE"\\u000Ain\\u000ANumber === true');  
+}
+
+//CHECK#7
+if (eval("'MAX_VALUE'\u000Din\u000DNumber") !== true) {
+  throw new Test262Error('#7: "MAX_VALUE"\\u000Din\\u000DNumber === true');
+}
+
+//CHECK#8
+if (eval("'MAX_VALUE'\u2028in\u2028Number") !== true) {
+  throw new Test262Error('#8: "MAX_VALUE"\\u2028in\\u2028Number === true');
+}
+
+//CHECK#9
+if (eval("'MAX_VALUE'\u2029in\u2029Number") !== true) {
+  throw new Test262Error('#9: "MAX_VALUE"\\u2029in\\u2029Number === true');
+}
+
+//CHECK#10
+if (eval("'MAX_VALUE'\u0009\u000B\u000C\u0020\u00A0\u000A\u000D\u2028\u2029in\u0009\u000B\u000C\u0020\u00A0\u000A\u000D\u2028\u2029Number") !== true) {
+  throw new Test262Error('#10: "MAX_VALUE"\\u0009\\u000B\\u000C\\u0020\\u00A0\\u000A\\u000D\\u2028\\u2029in\\u0009\\u000B\\u000C\\u0020\\u00A0\\u000A\\u000D\\u2028\\u2029Number === true');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T1.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T1.js
new file mode 100644
index 0000000000..97cff94304
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T1.js
@@ -0,0 +1,34 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: Operator "in" uses GetValue
+es5id: 11.8.7_A2.1_T1
+description: Either Expression is not Reference or GetBase is not null
+---*/
+
+//CHECK#1
+if ("MAX_VALUE" in Number !== true) {
+  throw new Test262Error('#1: "MAX_VALUE" in Number === true');
+}
+
+//CHECK#2
+var x = "MAX_VALUE";
+if (x in Number !== true) {
+  throw new Test262Error('#2: var x = "MAX_VALUE"; x in Number === true');
+}
+
+//CHECK#3
+var y = Number;
+if ("MAX_VALUE" in  y !== true) {
+  throw new Test262Error('#3: var y = Number; "MAX_VALUE" in y === true');
+}
+
+//CHECK#4
+var x = "MAX_VALUE";
+var y = Number;
+if (x in y !== true) {
+  throw new Test262Error('#4: var x = "MAX_VALUE"; var y = Number; x in y === true');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T2.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T2.js
new file mode 100644
index 0000000000..76bca7149e
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T2.js
@@ -0,0 +1,21 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: Operator "in" uses GetValue
+es5id: 11.8.7_A2.1_T2
+description: If GetBase(RelationalExpression) is null, throw ReferenceError
+---*/
+
+//CHECK#1
+try {
+  MAX_VALUE in Number;
+  throw new Test262Error('#1.1: MAX_VALUE in Number throw ReferenceError. Actual: ' + (MAX_VALUE in Number));  
+}
+catch (e) {
+  if ((e instanceof ReferenceError) !== true) {
+    throw new Test262Error('#1.2: MAX_VALUE in Number throw ReferenceError. Actual: ' + (e));  
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T3.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T3.js
new file mode 100644
index 0000000000..9b8129a6e6
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.1_T3.js
@@ -0,0 +1,21 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: Operator "in" uses GetValue
+es5id: 11.8.7_A2.1_T3
+description: If GetBase(ShiftExpression) is null, throw ReferenceError
+---*/
+
+//CHECK#1
+try {
+  "MAX_VALUE" in NUMBER;
+  throw new Test262Error('#1.1: "MAX_VALUE" in NUMBER throw ReferenceError. Actual: ' + ("MAX_VALUE" in NUMBER));  
+}
+catch (e) {
+  if ((e instanceof ReferenceError) !== true) {
+    throw new Test262Error('#1.2: "MAX_VALUE" in NUMBER throw ReferenceError. Actual: ' + (e));  
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T1.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T1.js
new file mode 100644
index 0000000000..60c526eba5
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T1.js
@@ -0,0 +1,22 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: First expression is evaluated first, and then second expression
+es5id: 11.8.7_A2.4_T1
+description: Checking with "="
+---*/
+
+//CHECK#1 
+var NUMBER = 0;
+if ((NUMBER = Number, "MAX_VALUE") in NUMBER !== true) {
+  throw new Test262Error('#1: var NUMBER = 0; (NUMBER = Number, "MAX_VALUE") in NUMBER === true');
+}
+
+//CHECK#2
+var max_value = "MAX_VALUE"; 
+if (max_value in (max_value = "none", Number) !== true) {
+  throw new Test262Error('#2: var max_value = "MAX_VALUE"; max_value in (max_value = "none", Number) === true');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T2.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T2.js
new file mode 100644
index 0000000000..5abcc342bc
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T2.js
@@ -0,0 +1,26 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: First expression is evaluated first, and then second expression
+es5id: 11.8.7_A2.4_T2
+description: Checking with "throw"
+---*/
+
+//CHECK#1
+var x = function () { throw "x"; };
+var y = function () { throw "y"; };
+try {
+   x() in y();
+   throw new Test262Error('#1.1: var x = function () { throw "x"; }; var y = function () { throw "y"; }; x() in y() throw "x". Actual: ' + (x() in y()));
+} catch (e) {
+   if (e === "y") {
+     throw new Test262Error('#1.2: First expression is evaluated first, and then second expression');
+   } else {
+     if (e !== "x") {
+       throw new Test262Error('#1.3: var x = function () { throw "x"; }; var y = function () { throw "y"; }; x() in y() throw "x". Actual: ' + (e));
+     }
+   }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T3.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T3.js
new file mode 100644
index 0000000000..01aa3bff03
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T3.js
@@ -0,0 +1,21 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: First expression is evaluated first, and then second expression
+es5id: 11.8.7_A2.4_T3
+description: Checking with undeclarated variables
+---*/
+
+//CHECK#1
+try {
+  max_value in (max_value = "MAX_VALUE", Number);
+  throw new Test262Error('#1.1: max_value in (max_value = "MAX_VALUE", Number) throw ReferenceError. Actual: ' + (max_value in (max_value = "MAX_VALUE", Number)));  
+}
+catch (e) {
+  if ((e instanceof ReferenceError) !== true) {
+    throw new Test262Error('#1.2: max_value in (max_value = "MAX_VALUE", Number) throw ReferenceError. Actual: ' + (e));  
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T4.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T4.js
new file mode 100644
index 0000000000..bdcd86784a
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A2.4_T4.js
@@ -0,0 +1,16 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: First expression is evaluated first, and then second expression
+es5id: 11.8.7_A2.4_T4
+description: Checking with undeclarated variables
+flags: [noStrict]
+---*/
+
+//CHECK#1
+if ((NUMBER = Number, "MAX_VALUE") in NUMBER !== true) {
+  throw new Test262Error('#1: (NUMBER = Number, "MAX_VALUE") in NUMBER !== true');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A3.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A3.js
new file mode 100644
index 0000000000..ea2be192d4
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A3.js
@@ -0,0 +1,65 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: If ShiftExpression is not an object, throw TypeError
+es5id: 11.8.7_A3
+description: Checking all the types of primitives
+---*/
+
+//CHECK#1
+try {
+  "toString" in true;
+  throw new Test262Error('#1: "toString" in true throw TypeError');  
+}
+catch (e) {
+  if ((e instanceof TypeError) !== true) {
+    throw new Test262Error('#1: "toString" in true throw TypeError');  
+  }
+}
+
+//CHECK#2
+try {
+  "MAX_VALUE" in 1;
+  throw new Test262Error('#2: "MAX_VALUE" in 1 throw TypeError');  
+}
+catch (e) {
+  if ((e instanceof TypeError) !== true) {
+    throw new Test262Error('#2: "MAX_VALUE" in 1 throw TypeError');  
+  }
+}
+
+//CHECK#3
+try {
+  "length" in "string";
+  throw new Test262Error('#3: "length" in "string" throw TypeError');  
+}
+catch (e) {
+  if ((e instanceof TypeError) !== true) {
+    throw new Test262Error('#3: "length" in "string" throw TypeError');  
+  }
+}
+
+//CHECK#4
+try {
+  "toString" in undefined;
+  throw new Test262Error('#4: "toString" in undefined throw TypeError');  
+}
+catch (e) {
+  if ((e instanceof TypeError) !== true) {
+    throw new Test262Error('#4: "toString" in undefined throw TypeError');  
+  }
+}
+
+//CHECK#5
+try {
+  "toString" in null;
+  throw new Test262Error('#5: "toString" in null throw TypeError');  
+}
+catch (e) {
+  if ((e instanceof TypeError) !== true) {
+    throw new Test262Error('#5: "toString" in null throw TypeError');  
+  }
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S11.8.7_A4.js b/js/src/tests/test262/language/expressions/in/S11.8.7_A4.js
new file mode 100644
index 0000000000..43c7f37227
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S11.8.7_A4.js
@@ -0,0 +1,38 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: Operator "in" calls ToString(ShiftExpression)
+es5id: 11.8.7_A4
+description: Checking ToString coversion;
+---*/
+
+//CHECK#1
+var object = {};
+object["true"] = 1;
+if (true in object !== "true" in object) {  
+  throw new Test262Error('#1: "var object = {}; object["true"] = 1; true in object === "true" in object');  
+}
+
+//CHECK#2
+var object = {};
+object.Infinity = 1;
+if (Infinity in object !== "Infinity" in object) {  
+  throw new Test262Error('#2: "var object = {}; object.Infinity = 1; Infinity in object === "Infinity" in object');  
+}
+
+//CHECK#4
+var object = {};
+object.undefined = 1;
+if (undefined in object !== "undefined" in object) {  
+  throw new Test262Error('#4: "var object = {}; object.undefined = 1; undefined in object === "undefined" in object');  
+}
+
+//CHECK#5
+var object = {};
+object["null"] = 1;
+if (null in object !== "null" in object) {  
+  throw new Test262Error('#5: "var object = {}; object["null"] = 1; null in object === "null" in object');  
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S8.12.6_A1.js b/js/src/tests/test262/language/expressions/in/S8.12.6_A1.js
new file mode 100644
index 0000000000..13ffeb62a5
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S8.12.6_A1.js
@@ -0,0 +1,22 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: |
+    When the [[HasProperty]] method of O is called with property name P and
+    if O has a property with name P, return true
+es5id: 8.12.6_A1
+description: Try find existent property of any Object
+---*/
+
+var __obj={fooProp:"fooooooo"};
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#1
+if (!("fooProp" in __obj)) {
+  throw new Test262Error('#1: var __obj={fooProp:"fooooooo"}; "fooProp" in __obj');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T1.js b/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T1.js
new file mode 100644
index 0000000000..64e1b60517
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T1.js
@@ -0,0 +1,22 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: |
+    When the [[HasProperty]] method of O is called with property name P and if O has not a property with name P
+    then If the [[Prototype]] of O is null, return false or call the [[HasProperty]] method of [[Prototype]] with property name P
+es5id: 8.12.6_A2_T1
+description: Try find not existent property of any Object
+---*/
+
+var __obj={};
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#1
+if (!("valueOf" in __obj)) {
+  throw new Test262Error('#1: var __obj={}; "valueOf" in __obj');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T2.js b/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T2.js
new file mode 100644
index 0000000000..b662ecedd7
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S8.12.6_A2_T2.js
@@ -0,0 +1,46 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: |
+    When the [[HasProperty]] method of O is called with property name P and if O has not a property with name P
+    then If the [[Prototype]] of O is null, return false or call the [[HasProperty]] method of [[Prototype]] with property name P
+es5id: 8.12.6_A2_T2
+description: >
+    Try find not existent property of any Object, but existent
+    property of this Object prototype
+---*/
+
+var __proto={phylum:"avis"};
+
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#1
+if (!("valueOf" in __proto)) {
+  throw new Test262Error('#1: var __proto={phylum:"avis"}; "valueOf" in __proto');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+function Robin(){this.name="robin"};
+Robin.prototype=__proto;
+
+var __my__robin = new Robin;
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#2
+if (!("phylum" in __my__robin)) {
+  throw new Test262Error('#2: var __proto={phylum:"avis"}; function Robin(){this.name="robin"}; Robin.prototype=__proto; var __my__robin = new Robin; "phylum" in __my__robin');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#3
+if (__my__robin.hasOwnProperty("phylum")) {
+  throw new Test262Error('#3: var __proto={phylum:"avis"}; function Robin(){this.name="robin"}; Robin.prototype=__proto; var __my__robin = new Robin; __my__robin.hasOwnProperty("phylum") === false. Actual: ' + (__my__robin.hasOwnProperty("phylum")));
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/S8.12.6_A3.js b/js/src/tests/test262/language/expressions/in/S8.12.6_A3.js
new file mode 100644
index 0000000000..c9aca7c8d7
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/S8.12.6_A3.js
@@ -0,0 +1,46 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+info: "[[hasProperty]] is sensitive to property existence but [[Get]] is not"
+es5id: 8.12.6_A3
+description: >
+    Use [[hasProperty]] and [[Get]] for existent and not existent
+    properties
+---*/
+
+var __obj={}; __obj.hole=undefined;
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#1
+if (__obj.hole !== undefined) {
+  throw new Test262Error('#1: var __obj={}; __obj.hole=undefined; __obj.hole === undefined. Actual: ' + (__obj.hole));
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#2
+if (__obj.notexist !== undefined) {
+  throw new Test262Error('#2: var __obj={}; __obj.hole=undefined; __obj.notexist === undefined. Actual: ' + (__obj.notexist));
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#3
+if (!("hole" in __obj)) {
+  throw new Test262Error('#3: var __obj={}; __obj.hole=undefined; "hole" in __obj');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+//////////////////////////////////////////////////////////////////////////////
+//CHECK#4
+if (("notexist" in __obj)) {
+  throw new Test262Error('#4: var __obj={}; __obj.hole=undefined; "notexist" in __obj');
+}
+//
+//////////////////////////////////////////////////////////////////////////////
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/browser.js b/js/src/tests/test262/language/expressions/in/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/browser.js
diff --git a/js/src/tests/test262/language/expressions/in/private-field-in-nested.js b/js/src/tests/test262/language/expressions/in/private-field-in-nested.js
new file mode 100644
index 0000000000..d49304e62e
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-in-nested.js
@@ -0,0 +1,28 @@
+// |reftest| error:SyntaxError
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Can't nest `in` expressions when the left-hand side is PrivateIdentifier.
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+esid: sec-relational-operators
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  constructor() {
+    #field in #field in this;
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-in.js b/js/src/tests/test262/language/expressions/in/private-field-in.js
new file mode 100644
index 0000000000..31a47f55ec
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-in.js
@@ -0,0 +1,27 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Requires the `In` parsing parameter
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  constructor() {
+    for (#field in value;;) break;
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-reference.js b/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-reference.js
new file mode 100644
index 0000000000..687165cc8d
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-reference.js
@@ -0,0 +1,26 @@
+// |reftest| error:SyntaxError
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Private identifiers aren't valid simple assignment references.
+info: |
+  Syntax
+    for ( LeftHandSideExpression in Expression ) Statement 
+esid: sec-for-in-and-for-of-statements-static-semantics-early-errors
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  m() {
+    for (#field in []) ;
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-target.js b/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-target.js
new file mode 100644
index 0000000000..d788f5d9e6
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-invalid-assignment-target.js
@@ -0,0 +1,32 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Rejected as assignment target
+info: |
+  12.10.5 Static Semantics: AllPrivateIdentifiersValid
+
+  AllPrivateIdentifiersValid is an abstract operation which takes names as an argument.
+
+  RelationalExpression:PrivateIdentifierinShiftExpression
+
+  1. If StringValue of PrivateIdentifier is in names, return true.
+  2. Return false.
+
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  constructor() {
+    #field in {} = 0;
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-complex.js b/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-complex.js
new file mode 100644
index 0000000000..802f539efe
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-complex.js
@@ -0,0 +1,32 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Invalid private identifier - complex case
+info: |
+  12.10.5 Static Semantics: AllPrivateIdentifiersValid
+
+  AllPrivateIdentifiersValid is an abstract operation which takes names as an argument.
+
+  RelationalExpression:PrivateIdentifierinShiftExpression
+
+  1. If StringValue of PrivateIdentifier is in names, return true.
+  2. Return false.
+
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #a;
+
+  constructor() {
+    #b in {};
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-simple.js b/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-simple.js
new file mode 100644
index 0000000000..db3365eea9
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-invalid-identifier-simple.js
@@ -0,0 +1,26 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Invalid private identifier - simple case
+info: |
+  12.10.5 Static Semantics: AllPrivateIdentifiersValid
+
+  AllPrivateIdentifiersValid is an abstract operation which takes names as an argument.
+
+  RelationalExpression:PrivateIdentifierinShiftExpression
+
+  1. If StringValue of PrivateIdentifier is in names, return true.
+  2. Return false.
+
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+#name in {};
diff --git a/js/src/tests/test262/language/expressions/in/private-field-invalid-rhs.js b/js/src/tests/test262/language/expressions/in/private-field-invalid-rhs.js
new file mode 100644
index 0000000000..fb8783d019
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-invalid-rhs.js
@@ -0,0 +1,27 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Syntactic grammar restricts right-hand side
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  constructor() {
+    #field in () => {};
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-accessor-shadowed.js b/js/src/tests/test262/language/expressions/in/private-field-presence-accessor-shadowed.js
new file mode 100644
index 0000000000..29a33b9b2d
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-accessor-shadowed.js
@@ -0,0 +1,49 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes an accessor method
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  [...]
+  10. Else,
+      a. Assert: privateName.[[Kind]] is "method" or "accessor".
+      b. If PrivateBrandCheck(rval, privateName) is not an abrupt completion,
+         then return true.
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-static-methods-private, class-fields-private-in]
+---*/
+
+let Child;
+let parentCount = 0;
+let childCount = 0;
+
+class Parent {
+  get #accessor() {
+    parentCount += 1;
+  }
+
+  static init() {
+    Child = class {
+      get #accessor() {
+        childCount += 1;
+      }
+
+      static isNameIn(value) {
+        return #accessor in value;
+      }
+    };
+  }
+}
+
+Parent.init();
+
+assert.sameValue(Child.isNameIn(new Parent()), false);
+assert.sameValue(parentCount, 0, 'parent accessor not invoked');
+assert.sameValue(Child.isNameIn(new Child()), true);
+assert.sameValue(childCount, 0, 'child accessor not invoked');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-accessor.js b/js/src/tests/test262/language/expressions/in/private-field-presence-accessor.js
new file mode 100644
index 0000000000..f684525631
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-accessor.js
@@ -0,0 +1,35 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes an accessor method
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  [...]
+  10. Else,
+      a. Assert: privateName.[[Kind]] is "method" or "accessor".
+      b. If PrivateBrandCheck(rval, privateName) is not an abrupt completion,
+         then return true.
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-static-methods-private, class-fields-private-in]
+---*/
+
+let count = 0;
+
+class Class {
+  get #accessor() {
+    count += 1;
+  }
+
+  static isNameIn(value) {
+    return #accessor in value;
+  }
+}
+
+assert.sameValue(Class.isNameIn({}), false);
+assert.sameValue(Class.isNameIn(new Class()), true);
+assert.sameValue(count, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-field-shadowed.js b/js/src/tests/test262/language/expressions/in/private-field-presence-field-shadowed.js
new file mode 100644
index 0000000000..805ce61193
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-field-shadowed.js
@@ -0,0 +1,38 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes a field
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  9. If privateName.[[Kind]] is "field",
+     a. If ! PrivateFieldFind(privateName, rval) is not empty, then return true.
+  [...]
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+let Child;
+
+class Parent {
+  #field;
+
+  static init() {
+    Child = class {
+      #field;
+
+      static isNameIn(value) {
+        return #field in value;
+      }
+    };
+  }
+}
+
+Parent.init();
+
+assert.sameValue(Child.isNameIn(new Parent()), false);
+assert.sameValue(Child.isNameIn(new Child()), true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-field.js b/js/src/tests/test262/language/expressions/in/private-field-presence-field.js
new file mode 100644
index 0000000000..50a24a6aa5
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-field.js
@@ -0,0 +1,28 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes a field
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  9. If privateName.[[Kind]] is "field",
+     a. If ! PrivateFieldFind(privateName, rval) is not empty, then return true.
+  [...]
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+class Class {
+  #field;
+
+  static isNameIn(value) {
+    return #field in value;
+  }
+}
+
+assert.sameValue(Class.isNameIn({}), false);
+assert.sameValue(Class.isNameIn(new Class()), true);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-method-shadowed.js b/js/src/tests/test262/language/expressions/in/private-field-presence-method-shadowed.js
new file mode 100644
index 0000000000..7d12504b05
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-method-shadowed.js
@@ -0,0 +1,48 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes a method
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  [...]
+  10. Else,
+      a. Assert: privateName.[[Kind]] is "method" or "accessor".
+      b. If PrivateBrandCheck(rval, privateName) is not an abrupt completion,
+         then return true.
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-methods-private, class-fields-private-in]
+---*/
+
+let Child;
+let parentCount = 0;
+let childCount = 0;
+
+class Parent {
+  #method() {
+    parentCount += 1;
+  }
+
+  static init() {
+    Child = class {
+      #method() {
+        childCount += 1;
+      }
+
+      static isNameIn(value) {
+        return #method in value;
+      }
+    };
+  }
+}
+
+Parent.init();
+
+assert.sameValue(Child.isNameIn(new Parent()), false);
+assert.sameValue(parentCount, 0, 'parent method not invoked');
+assert.sameValue(Child.isNameIn(new Child()), true);
+assert.sameValue(childCount, 0, 'child method not invoked');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-presence-method.js b/js/src/tests/test262/language/expressions/in/private-field-presence-method.js
new file mode 100644
index 0000000000..c736fa5a95
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-presence-method.js
@@ -0,0 +1,35 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Value when private name describes a method
+info: |
+  7. Let privateName be ? GetValue(privateNameBinding).
+  8. Assert: privateName is a Private Name.
+  [...]
+  10. Else,
+      a. Assert: privateName.[[Kind]] is "method" or "accessor".
+      b. If PrivateBrandCheck(rval, privateName) is not an abrupt completion,
+         then return true.
+  11. Return false.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-methods-private, class-fields-private-in]
+---*/
+
+let count = 0;
+
+class Class {
+  #method() {
+    count += 1;
+  }
+
+  static isNameIn(value) {
+    return #method in value;
+  }
+}
+
+assert.sameValue(Class.isNameIn({}), false);
+assert.sameValue(Class.isNameIn(new Class()), true);
+assert.sameValue(count, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-await-absent.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-await-absent.js
new file mode 100644
index 0000000000..c2b12ad402
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-await-absent.js
@@ -0,0 +1,41 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Await` production parameter when absent
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+  4. If Type(rval) is not Object, throw a TypeError exception.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+let value;
+function await() {
+  return value;
+}
+
+class C {
+  #field;
+
+  static isNameIn() {
+    return #field in await(null);
+  }
+}
+
+value = new C();
+assert.sameValue(C.isNameIn(), true);
+
+value = {};
+assert.sameValue(C.isNameIn(), false);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-await-present.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-await-present.js
new file mode 100644
index 0000000000..a67c90218d
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-await-present.js
@@ -0,0 +1,40 @@
+// |reftest| async
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Await` production parameter when present
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+  4. If Type(rval) is not Object, throw a TypeError exception.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+flags: [async]
+---*/
+
+class C {
+  #field;
+
+  static async isNameIn(value) {
+    return #field in await(value);
+  }
+}
+
+C.isNameIn(new C())
+  .then(function(result) {
+    assert.sameValue(result, true);
+
+    return C.isNameIn({});
+  })
+  .then(function(result) {
+    assert.sameValue(result, false);
+  }).then($DONE, $DONE);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-non-object.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-non-object.js
new file mode 100644
index 0000000000..db510e2106
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-non-object.js
@@ -0,0 +1,53 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Algorithm interrupted by non-object right-hand side
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+  4. If Type(rval) is not Object, throw a TypeError exception.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+let caught = null;
+
+class C {
+  #field;
+
+  constructor() {
+    try {
+      /**
+       * Using a ShiftExpression to produce the non-object value verifies that
+       * the implementation uses the operator precedence implied by the
+       * syntactic grammar. In other words, the following statement should be
+       * interpreted as:
+       *
+       *     #field in ({} << 0);
+       *
+       * ...rather than:
+       *
+       *     (#field in {}) << 0;
+       */
+      #field in {} << 0;
+    } catch (error) {
+      caught = error;
+    }
+  }
+}
+
+new C();
+
+assert.notSameValue(caught, null);
+assert.sameValue(caught.constructor, TypeError);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-unresolvable.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-unresolvable.js
new file mode 100644
index 0000000000..f76cd96882
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-unresolvable.js
@@ -0,0 +1,32 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Algorithm interrupted by unresolvable reference
+info: |
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+let caught = null;
+
+class C {
+  #field;
+  constructor() {
+    try {
+      #field in test262unresolvable;
+    } catch (error) {
+      caught = error;
+    }
+  }
+}
+
+new C();
+
+assert.notSameValue(caught, null);
+assert.sameValue(caught.constructor, ReferenceError);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-absent.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-absent.js
new file mode 100644
index 0000000000..77ee26a61f
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-absent.js
@@ -0,0 +1,34 @@
+// |reftest| error:SyntaxError
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Yield` production parameter when present
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+  4. If Type(rval) is not Object, throw a TypeError exception.
+esid: sec-relational-operators-runtime-semantics-evaluation
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  static method() {
+    #field in yield;
+  }
+}
diff --git a/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-present.js b/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-present.js
new file mode 100644
index 0000000000..7ab2272328
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/private-field-rhs-yield-present.js
@@ -0,0 +1,38 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Yield` production parameter when present
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let privateIdentifier be the StringValue of PrivateIdentifier.
+  2. Let rref be the result of evaluating ShiftExpression.
+  3. Let rval be ? GetValue(rref).
+  4. If Type(rval) is not Object, throw a TypeError exception.
+esid: sec-relational-operators-runtime-semantics-evaluation
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+class C {
+  #field;
+
+  static *isNameIn() {
+    return #field in (yield);
+  }
+}
+
+let iter1 = C.isNameIn();
+iter1.next();
+assert.sameValue(iter1.next(new C()).value, true);
+
+let iter2 = C.isNameIn();
+iter2.next();
+assert.sameValue(iter2.next({}).value, false);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/rhs-yield-absent-non-strict.js b/js/src/tests/test262/language/expressions/in/rhs-yield-absent-non-strict.js
new file mode 100644
index 0000000000..7e5cbae2b2
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/rhs-yield-absent-non-strict.js
@@ -0,0 +1,32 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Yield` production parameter when absent (without strict mode)
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In] RelationalExpression[+In, ?Yield, ?Await] in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let lref be the result of evaluating RelationalExpression.
+  2. Let lval be ? GetValue(lref).
+  3. Let rref be the result of evaluating ShiftExpression.
+  4. Let rval be ? GetValue(rref).
+  5. If Type(rval) is not Object, throw a TypeError exception.
+  6. Return ? HasProperty(rval, ? ToPropertyKey(lval)).
+esid: sec-relational-operators
+flags: [noStrict]
+---*/
+
+var yield;
+
+yield = {'': 0};
+assert.sameValue('' in (yield), true);
+
+yield = {};
+assert.sameValue('' in (yield), false);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/rhs-yield-absent-strict-strict.js b/js/src/tests/test262/language/expressions/in/rhs-yield-absent-strict-strict.js
new file mode 100644
index 0000000000..cac0db7e1d
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/rhs-yield-absent-strict-strict.js
@@ -0,0 +1,22 @@
+// |reftest| error:SyntaxError
+'use strict';
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Yield` production parameter when absent (within strict mode)
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In] RelationalExpression[+In, ?Yield, ?Await] in ShiftExpression[?Yield, ?Await]
+esid: sec-relational-operators
+negative:
+  phase: parse
+  type: SyntaxError
+flags: [onlyStrict]
+---*/
+
+$DONOTEVALUATE();
+
+'' in (yield);
diff --git a/js/src/tests/test262/language/expressions/in/rhs-yield-present.js b/js/src/tests/test262/language/expressions/in/rhs-yield-present.js
new file mode 100644
index 0000000000..e3fec252bd
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/rhs-yield-present.js
@@ -0,0 +1,35 @@
+// Copyright 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Parsing observes the `Yield` production parameter when present
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In] RelationalExpression[+In, ?Yield, ?Await] in ShiftExpression[?Yield, ?Await]
+
+  [...]
+
+  1. Let lref be the result of evaluating RelationalExpression.
+  2. Let lval be ? GetValue(lref).
+  3. Let rref be the result of evaluating ShiftExpression.
+  4. Let rval be ? GetValue(rref).
+  5. If Type(rval) is not Object, throw a TypeError exception.
+  6. Return ? HasProperty(rval, ? ToPropertyKey(lval)).
+esid: sec-relational-operators-runtime-semantics-evaluation
+---*/
+
+function * isNameIn() {
+  return '' in (yield);
+}
+
+let iter1 = isNameIn();
+iter1.next();
+assert.sameValue(iter1.next({'': 0}).value, true);
+
+let iter2 = isNameIn();
+iter2.next();
+assert.sameValue(iter2.next({}).value, false);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/language/expressions/in/shell.js b/js/src/tests/test262/language/expressions/in/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/language/expressions/in/shell.js