v8/test/mjsunit/harmony/block-let-declaration.js

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// Flags: --harmony-scoping

// Test let declarations in various settings.
// TODO(ES6): properly activate extended mode
"use strict";

// Global
let x;
let y = 2;
const z = 4;

// Block local
{
  let y;
  let x = 3;
  const z = 5;
}

assertEquals(undefined, x);
assertEquals(2,y);
assertEquals(4,z);

if (true) {
  let y;
  assertEquals(undefined, y);
}

// Invalid declarations are early errors in harmony mode and thus should trigger
// an exception in eval code during parsing, before even compiling or executing
// the code. Thus the generated function is not called here.
function TestLocalThrows(str, expect) {
  assertThrows("(function(){ 'use strict'; " + str + "})", expect);
}

function TestLocalDoesNotThrow(str) {
  assertDoesNotThrow("(function(){ 'use strict'; " + str + "})()");
}

// Test let declarations in statement positions.
TestLocalThrows("if (true) let x;", SyntaxError);
TestLocalThrows("if (true) {} else let x;", SyntaxError);
TestLocalThrows("do let x; while (false)", SyntaxError);
TestLocalThrows("while (false) let x;", SyntaxError);
TestLocalThrows("label: let x;", SyntaxError);
TestLocalThrows("for (;false;) let x;", SyntaxError);
TestLocalThrows("switch (true) { case true: let x; }", SyntaxError);
TestLocalThrows("switch (true) { default: let x; }", SyntaxError);

// Test const declarations with initialisers in statement positions.
TestLocalThrows("if (true) const x = 1;", SyntaxError);
TestLocalThrows("if (true) {} else const x = 1;", SyntaxError);
TestLocalThrows("do const x = 1; while (false)", SyntaxError);
TestLocalThrows("while (false) const x = 1;", SyntaxError);
TestLocalThrows("label: const x = 1;", SyntaxError);
TestLocalThrows("for (;false;) const x = 1;", SyntaxError);
TestLocalThrows("switch (true) { case true: const x = 1; }", SyntaxError);
TestLocalThrows("switch (true) { default: const x = 1; }", SyntaxError);

// Test const declarations without initialisers.
TestLocalThrows("const x;", SyntaxError);
TestLocalThrows("const x = 1, y;", SyntaxError);
TestLocalThrows("const x, y = 1;", SyntaxError);

// Test const declarations without initialisers in statement positions.
TestLocalThrows("if (true) const x;", SyntaxError);
TestLocalThrows("if (true) {} else const x;", SyntaxError);
TestLocalThrows("do const x; while (false)", SyntaxError);
TestLocalThrows("while (false) const x;", SyntaxError);
TestLocalThrows("label: const x;", SyntaxError);
TestLocalThrows("for (;false;) const x;", SyntaxError);
TestLocalThrows("switch (true) { case true: const x; }", SyntaxError);
TestLocalThrows("switch (true) { default: const x; }", SyntaxError);

// Test var declarations in statement positions.
TestLocalDoesNotThrow("if (true) var x;");
TestLocalDoesNotThrow("if (true) {} else var x;");
TestLocalDoesNotThrow("do var x; while (false)");
TestLocalDoesNotThrow("while (false) var x;");
TestLocalDoesNotThrow("label: var x;");
TestLocalDoesNotThrow("for (;false;) var x;");
TestLocalDoesNotThrow("switch (true) { case true: var x; }");
TestLocalDoesNotThrow("switch (true) { default: var x; }");

// Test function declarations in source element and
// non-strict statement positions.
function f() {
  // Non-strict source element positions.
  function g0() {
    "use strict";
    // Strict source element positions.
    function h() { }
    {
      function h1() { }
    }
  }
  {
    function g1() { }
  }
}
f();

// Test function declarations in statement position in strict mode.
TestLocalThrows("function f() { if (true) function g() {}", SyntaxError);
TestLocalThrows("function f() { if (true) {} else function g() {}", SyntaxError);
TestLocalThrows("function f() { do function g() {} while (false)", SyntaxError);
TestLocalThrows("function f() { while (false) function g() {}", SyntaxError);
TestLocalThrows("function f() { label: function g() {}", SyntaxError);
TestLocalThrows("function f() { for (;false;) function g() {}", SyntaxError);
TestLocalThrows("function f() { switch (true) { case true: function g() {} }", SyntaxError);
TestLocalThrows("function f() { switch (true) { default: function g() {} }", SyntaxError);