diff --git a/test/built-ins/TypedArray/prototype/findIndex/get-length-ignores-length-prop.js b/test/built-ins/TypedArray/prototype/findIndex/get-length-ignores-length-prop.js
new file mode 100644
index 0000000000..bbcbb767b0
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/get-length-ignores-length-prop.js
@@ -0,0 +1,52 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  [[Get]] of "length" uses [[ArrayLength]]
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  2. Let len be ? ToLength(? Get(O, "length")).
+  ...
+includes: [testTypedArray.js]
+---*/
+
+Object.defineProperty(TypedArray.prototype, "length", {
+  get: function() {
+    throw new Test262Error();
+  }
+});
+
+testWithTypedArrayConstructors(function(TA) {
+  Object.defineProperty(TA.prototype, "length", {
+    get: function() {
+      throw new Test262Error();
+    }
+  });
+
+  var sample = new TA([42]);
+
+  Object.defineProperty(sample, "length", {
+    get: function() {
+      throw new Test262Error();
+    },
+    configurable: true
+  });
+
+  assert.sameValue(
+    sample.findIndex(function() { return true; }),
+    0
+  );
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-call-changes-value.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-changes-value.js
new file mode 100644
index 0000000000..c35504751f
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-changes-value.js
@@ -0,0 +1,67 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Change values during predicate call
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+includes: [compareArray.js, testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var arr = [10, 20, 30];
+  var sample;
+  var result;
+
+  sample = new TA(3);
+  sample.findIndex(function(val, i) {
+    sample[i] = arr[i];
+
+    assert.sameValue(val, 0, "value is not mapped to instance");
+  });
+  assert(compareArray(sample, arr), "values set during each predicate call");
+
+  sample = new TA(arr);
+  result = sample.findIndex(function(val, i) {
+    if ( i === 0 ) {
+      sample[2] = 7;
+    }
+    return val === 7;
+  });
+  assert.sameValue(result, 2, "value found");
+
+  sample = new TA(arr);
+  result = sample.findIndex(function(val, i) {
+    if ( i === 0 ) {
+      sample[2] = 7;
+    }
+    return val === 30;
+  });
+  assert.sameValue(result, -1, "value not found");
+
+  sample = new TA(arr);
+  result = sample.findIndex(function(val, i) {
+    if ( i > 0 ) {
+      sample[0] = 7;
+    }
+    return val === 7;
+  });
+  assert.sameValue(result, -1, "value not found - changed after call");
+});
\ No newline at end of file
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-call-parameters.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-parameters.js
new file mode 100644
index 0000000000..0e0a6c786c
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-parameters.js
@@ -0,0 +1,60 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Predicate called as F.call( thisArg, kValue, k, O ) for each array entry.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  4. If thisArg was supplied, let T be thisArg; else let T be undefined.
+  5. Let k be 0.
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA([39, 2, 62]);
+  var results = [];
+  var result;
+
+  sample.foo = "bar"; // Ignores non integer index properties
+
+  sample.findIndex(function() {
+    results.push(arguments);
+  });
+
+  assert.sameValue(results.length, 3, "predicate is called for each index");
+
+  result = results[0];
+  assert.sameValue(result[0], 39, "results[0][0] === 39, value");
+  assert.sameValue(result[1], 0, "results[0][1] === 0, index");
+  assert.sameValue(result[2], sample, "results[0][2] === sample, instance");
+  assert.sameValue(result.length, 3, "results[0].length === 3, arguments");
+
+  result = results[1];
+  assert.sameValue(result[0], 2, "results[1][0] === 2, value");
+  assert.sameValue(result[1], 1, "results[1][1] === 1, index");
+  assert.sameValue(result[2], sample, "results[1][2] === sample, instance");
+  assert.sameValue(result.length, 3, "results[1].length === 3, arguments");
+
+  result = results[2];
+  assert.sameValue(result[0], 62, "results[2][0] === 62, value");
+  assert.sameValue(result[1], 2, "results[2][1] === 2, index");
+  assert.sameValue(result[2], sample, "results[2][2] === sample, instance");
+  assert.sameValue(result.length, 3, "results[2].length === 3, arguments");
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-non-strict.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-non-strict.js
new file mode 100644
index 0000000000..b4fe458eba
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-non-strict.js
@@ -0,0 +1,57 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Verify predicate this on non-strict mode
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  4. If thisArg was supplied, let T be thisArg; else let T be undefined.
+  5. Let k be 0.
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+flags: [noStrict]
+includes: [testTypedArray.js]
+---*/
+
+var T = this;
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(1);
+  var result;
+
+  sample.findIndex(function() {
+    result = this;
+  });
+
+  assert.sameValue(result, T, "without thisArg, predicate this is the global");
+
+  result = null;  
+  sample.findIndex(function() {
+    result = this;
+  }, undefined);
+
+  assert.sameValue(result, T, "predicate this is the global when thisArg is undefined");
+
+  var o = {};
+  result = null;
+  sample.findIndex(function() {
+    result = this;
+  }, o);
+
+  assert.sameValue(result, o, "thisArg becomes the predicate this");
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-strict.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-strict.js
new file mode 100644
index 0000000000..a443937e54
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-call-this-strict.js
@@ -0,0 +1,51 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Predicate thisArg as F.call( thisArg, kValue, k, O ) for each array entry.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  4. If thisArg was supplied, let T be thisArg; else let T be undefined.
+  5. Let k be 0.
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+flags: [onlyStrict]
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(1);
+  var result;
+
+  sample.findIndex(function() {
+    result = this;
+  });
+
+  assert.sameValue(
+    result,
+    undefined,
+    "without thisArg, predicate this is undefined"
+  );
+
+  var o = {};
+  sample.findIndex(function() {
+    result = this;
+  }, o);
+
+  assert.sameValue(result, o, "thisArg becomes the predicate this");
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-is-not-callable-throws.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-is-not-callable-throws.js
new file mode 100644
index 0000000000..ec250f4552
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-is-not-callable-throws.js
@@ -0,0 +1,64 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Throws a TypeError exception if predicate is not callable.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  3. If IsCallable(predicate) is false, throw a TypeError exception.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA();
+  assert.throws(TypeError, function() {
+    sample.findIndex({});
+  }, "{}");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(null);
+  }, "null");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(undefined);
+  }, "undefined");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(false);
+  }, "false");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(true);
+  }, "true");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(1);
+  }, "1");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex("");
+  }, "string");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex([]);
+  }, "[]");
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(/./);
+  }, "/./");
+});
+
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-may-detach-buffer.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-may-detach-buffer.js
new file mode 100644
index 0000000000..8b964d4eea
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-may-detach-buffer.js
@@ -0,0 +1,51 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Predicate may detach the buffer
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  6. Repeat, while k < len
+    ...
+    b. Let kValue be ? Get(O, Pk).
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+
+  9.4.5.8 IntegerIndexedElementGet ( O, index )
+
+  ...
+  3. Let buffer be the value of O's [[ViewedArrayBuffer]] internal slot.
+  4. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
+  ...
+includes: [testTypedArray.js, detachArrayBuffer.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(2);
+  var loops = 0;
+  var completion = false;
+
+  assert.throws(TypeError, function() {
+    sample.findIndex(function() {
+      loops++;
+      $DETACHBUFFER(sample.buffer);
+      completion = true;
+    });
+  }, "throws a TypeError getting a value from the detached buffer");
+
+  assert.sameValue(loops, 1, "predicated is called once");
+  assert(completion, "abrupt completion does not come from DETACHBUFFER");
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/predicate-not-called-on-empty-array.js b/test/built-ins/TypedArray/prototype/findIndex/predicate-not-called-on-empty-array.js
new file mode 100644
index 0000000000..8b99424781
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/predicate-not-called-on-empty-array.js
@@ -0,0 +1,48 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Predicate is not called on an empty instance
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+  7. Return -1.
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA();
+  var called = false;
+
+  var predicate = function() {
+    called = true;
+    return true;
+  };
+
+  var result = sample.findIndex(predicate);
+
+  assert.sameValue(
+    called, false,
+    "does not call predicate"
+  );
+  assert.sameValue(
+    result, -1,
+    "returns -1 on an empty instance"
+  );
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/return-abrupt-from-predicate-call.js b/test/built-ins/TypedArray/prototype/findIndex/return-abrupt-from-predicate-call.js
new file mode 100644
index 0000000000..1fca00db22
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/return-abrupt-from-predicate-call.js
@@ -0,0 +1,38 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Return abrupt from predicate call.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  5. Let k be 0.
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+includes: [testTypedArray.js]
+---*/
+
+var predicate = function() {
+  throw new Test262Error();
+};
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(1);
+  assert.throws(Test262Error, function() {
+    sample.findIndex(predicate);
+  });
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/return-index-predicate-result-is-true.js b/test/built-ins/TypedArray/prototype/findIndex/return-index-predicate-result-is-true.js
new file mode 100644
index 0000000000..8a4940641c
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/return-index-predicate-result-is-true.js
@@ -0,0 +1,66 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Return index if predicate return a boolean true value.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  5. Let k be 0.
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+    d. If testResult is true, return k.
+  ...
+features: [Symbol]
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA([39, 3, 9]);
+  var called = 0;
+
+  var result = sample.findIndex(function() {
+    called++;
+    return true;
+  });
+
+  assert.sameValue(result, 0, "returned true on sample[0]");
+  assert.sameValue(called, 1, "predicate was called once");
+
+  called = 0;
+  result = sample.findIndex(function(val) {
+    called++;
+    return val === 9;
+  });
+
+  assert.sameValue(called, 3, "predicate was called three times");
+  assert.sameValue(result, 2, "returned true on sample[3]");
+
+  result = sample.findIndex(function() { return "string"; });
+  assert.sameValue(result, 0, "ToBoolean(string)");
+
+  result = sample.findIndex(function() { return {}; });
+  assert.sameValue(result, 0, "ToBoolean(object)");
+
+  result = sample.findIndex(function() { return Symbol(""); });
+  assert.sameValue(result, 0, "ToBoolean(symbol)");
+
+  result = sample.findIndex(function() { return 1; });
+  assert.sameValue(result, 0, "ToBoolean(number)");
+
+  result = sample.findIndex(function() { return -1; });
+  assert.sameValue(result, 0, "ToBoolean(negative number)");
+});
diff --git a/test/built-ins/TypedArray/prototype/findIndex/return-negative-one-if-predicate-returns-false-value.js b/test/built-ins/TypedArray/prototype/findIndex/return-negative-one-if-predicate-returns-false-value.js
new file mode 100644
index 0000000000..400d05721b
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/findIndex/return-negative-one-if-predicate-returns-false-value.js
@@ -0,0 +1,58 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.findindex
+es6id: 22.2.3.11
+description: >
+  Return -1 if predicate always returns a boolean false value.
+info: >
+  22.2.3.11 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )
+
+  %TypedArray%.prototype.findIndex is a distinct function that implements the
+  same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that
+  the this object's [[ArrayLength]] internal slot is accessed in place of
+  performing a [[Get]] of "length".
+
+  ...
+
+  22.1.3.9 Array.prototype.findIndex ( predicate[ , thisArg ] )
+
+  ...
+  6. Repeat, while k < len
+    ...
+    c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+  ...
+  7. Return -1.
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA([1, 2, 3]);
+  var called = 0;
+
+  var result = sample.findIndex(function(val) {
+    called++;
+    return false;
+  });
+
+  assert.sameValue(called, 3, "predicate was called three times");
+  assert.sameValue(result, -1, "result is -1 when predicate returns are false");
+
+  result = sample.findIndex(function(val) { return ""; });
+  assert.sameValue(result, -1, "ToBoolean(string)");
+
+  result = sample.findIndex(function(val) { return undefined; });
+  assert.sameValue(result, -1, "ToBoolean(undefined)");
+
+  result = sample.findIndex(function(val) { return null; });
+  assert.sameValue(result, -1, "ToBoolean(null)");
+
+  result = sample.findIndex(function(val) { return 0; });
+  assert.sameValue(result, -1, "ToBoolean(0)");
+
+  result = sample.findIndex(function(val) { return -0; });
+  assert.sameValue(result, -1, "ToBoolean(-0)");
+
+  result = sample.findIndex(function(val) { return NaN; });
+  assert.sameValue(result, -1, "ToBoolean(NaN)");
+});