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Edit File: const-redecl.js
// Copyright 2008 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // Test for const semantics. function CheckException(e) { var string = e.toString(); var index = string.indexOf(':'); assertTrue(index >= 0); var name = string.slice(0, index); assertTrue(string.indexOf("has already been declared") >= 0 || string.indexOf("redeclaration") >= 0); if (name == 'SyntaxError') return 'TypeError'; return name; } function TestLocal(s,e) { try { return eval("(function(){" + s + ";return " + e + "})")(); } catch (x) { return CheckException(x); } } // NOTE: TestGlobal usually only tests the given string in the context // of a global object in dictionary mode. This is because we use // delete to get rid of any added properties. function TestGlobal(s,e) { // Collect the global properties before the call. var properties = []; for (var key in this) properties.push(key); // Compute the result. var result; try { var code = s + (e ? "; $$$result=" + e : ""); if (this.execScript) { execScript(code); } else { this.eval(code); } // Avoid issues if $$$result is not defined by // reading it through this. result = this.$$$result; } catch (x) { result = CheckException(x); } // Get rid of any introduced global properties before // returning the result. for (var key in this) { if (properties.indexOf(key) == -1) delete this[key]; } return result; } function TestContext(s,e) { try { // Use a with-statement to force the system to do dynamic // declarations of the introduced variables or constants. with ({}) { return eval(s + ";" + e); } } catch (x) { return CheckException(x); } } function TestAll(expected,s,opt_e) { var e = ""; var msg = s; if (opt_e) { e = opt_e; msg += "; " + opt_e; } assertEquals(expected, TestLocal(s,e), "local:'" + msg + "'"); // Redeclarations of global consts do not throw, they are silently ignored. assertEquals(42, TestGlobal(s, 42), "global:'" + msg + "'"); assertEquals(expected, TestContext(s,e), "context:'" + msg + "'"); } function TestConflict(def0, def1) { // No eval. TestAll("TypeError", def0 +'; ' + def1); // Eval everything. TestAll("TypeError", 'eval("' + def0 + '; ' + def1 + '")'); // Eval first definition. TestAll("TypeError", 'eval("' + def0 +'"); ' + def1); // Eval second definition. TestAll("TypeError", def0 + '; eval("' + def1 + '")'); // Eval both definitions separately. TestAll("TypeError", 'eval("' + def0 +'"); eval("' + def1 + '")'); } // Test conflicting definitions. TestConflict("const x", "var x"); TestConflict("const x = 0", "var x"); TestConflict("const x", "var x = 0"); TestConflict("const x = 0", "var x = 0"); TestConflict("var x", "const x"); TestConflict("var x = 0", "const x"); TestConflict("var x", "const x = 0"); TestConflict("var x = 0", "const x = 0"); TestConflict("const x = undefined", "var x"); TestConflict("const x", "var x = undefined"); TestConflict("const x = undefined", "var x = undefined"); TestConflict("var x = undefined", "const x"); TestConflict("var x", "const x = undefined"); TestConflict("var x = undefined", "const x = undefined"); TestConflict("const x = undefined", "var x = 0"); TestConflict("const x = 0", "var x = undefined"); TestConflict("var x = undefined", "const x = 0"); TestConflict("var x = 0", "const x = undefined"); TestConflict("const x", "function x() { }"); TestConflict("const x = 0", "function x() { }"); TestConflict("const x = undefined", "function x() { }"); TestConflict("function x() { }", "const x"); TestConflict("function x() { }", "const x = 0"); TestConflict("function x() { }", "const x = undefined"); TestConflict("const x, y", "var x"); TestConflict("const x, y", "var y"); TestConflict("const x = 0, y", "var x"); TestConflict("const x = 0, y", "var y"); TestConflict("const x, y = 0", "var x"); TestConflict("const x, y = 0", "var y"); TestConflict("const x = 0, y = 0", "var x"); TestConflict("const x = 0, y = 0", "var y"); TestConflict("var x", "const x, y"); TestConflict("var y", "const x, y"); TestConflict("var x", "const x = 0, y"); TestConflict("var y", "const x = 0, y"); TestConflict("var x", "const x, y = 0"); TestConflict("var y", "const x, y = 0"); TestConflict("var x", "const x = 0, y = 0"); TestConflict("var y", "const x = 0, y = 0"); // Test that multiple conflicts do not cause issues. TestConflict("var x, y", "const x, y"); // Test that repeated const declarations throw redeclaration errors. TestConflict("const x", "const x"); TestConflict("const x = 0", "const x"); TestConflict("const x", "const x = 0"); TestConflict("const x = 0", "const x = 0"); TestConflict("const x = undefined", "const x"); TestConflict("const x", "const x = undefined"); TestConflict("const x = undefined", "const x = undefined"); TestConflict("const x = undefined", "const x = 0"); TestConflict("const x = 0", "const x = undefined"); TestConflict("const x, y", "const x"); TestConflict("const x, y", "const y"); TestConflict("const x = 0, y", "const x"); TestConflict("const x = 0, y", "const y"); TestConflict("const x, y = 0", "const x"); TestConflict("const x, y = 0", "const y"); TestConflict("const x = 0, y = 0", "const x"); TestConflict("const x = 0, y = 0", "const y"); TestConflict("const x", "const x, y"); TestConflict("const y", "const x, y"); TestConflict("const x", "const x = 0, y"); TestConflict("const y", "const x = 0, y"); TestConflict("const x", "const x, y = 0"); TestConflict("const y", "const x, y = 0"); TestConflict("const x", "const x = 0, y = 0"); TestConflict("const y", "const x = 0, y = 0"); // Test that multiple const conflicts do not cause issues. TestConflict("const x, y", "const x, y"); // Test that const inside loop behaves correctly. var loop = "for (var i = 0; i < 3; i++) { const x = i; }"; TestAll(0, loop, "x"); TestAll(0, "var a,b,c,d,e,f,g,h; " + loop, "x"); // Test that const inside with behaves correctly. TestAll(87, "with ({x:42}) { const x = 87; }", "x"); TestAll(undefined, "with ({x:42}) { const x; }", "x"); // Additional tests for how various combinations of re-declarations affect // the values of the var/const in question. try { eval("var undefined;"); } catch (ex) { assertUnreachable("undefined (1) has thrown"); } var original_undef = undefined; var undefined = 1; // Should be silently ignored. assertEquals(original_undef, undefined, "undefined got overwritten"); undefined = original_undef; var a; const a; const a = 1; assertEquals(1, a, "a has wrong value"); a = 2; assertEquals(2, a, "a should be writable"); var b = 1; const b = 2; assertEquals(2, b, "b has wrong value"); var c = 1; const c = 2; const c = 3; assertEquals(3, c, "c has wrong value"); const d = 1; const d = 2; assertEquals(1, d, "d has wrong value"); const e = 1; var e = 2; assertEquals(1, e, "e has wrong value"); const f = 1; const f; assertEquals(1, f, "f has wrong value"); var g; const g = 1; assertEquals(1, g, "g has wrong value"); g = 2; assertEquals(2, g, "g should be writable"); const h; var h = 1; assertEquals(undefined,h, "h has wrong value"); eval("Object.defineProperty(this, 'i', { writable: true });" + "const i = 7;" + "assertEquals(7, i, \"i has wrong value\");"); var global = this; assertThrows(function() { Object.defineProperty(global, 'j', { writable: true }) }, TypeError); const j = 2; // This is what makes the function above throw, because the // const declaration gets hoisted and makes the property non-configurable. assertEquals(2, j, "j has wrong value"); var k = 1; const k; // You could argue about the expected result here. For now, the winning // argument is that "const k;" is equivalent to "const k = undefined;". assertEquals(undefined, k, "k has wrong value");