LayoutTests/cssom/observable-array-delete.html

<!DOCTYPE html>
<html>
<body>
<script src="../resources/js-test.js"></script>
<script>
description("Tests for ObservableArray's [[Delete]]");

let sheet1 = null;
let sheet2 = null;
let sheet3 = null;

function runTest() {
    "use strict";

    sheet1 = new CSSStyleSheet()
    sheet1.replaceSync('div { color: red }')
    document.adoptedStyleSheets.push(sheet1)

    sheet2 = new CSSStyleSheet()
    sheet2.replaceSync('div { color: blue }')
    document.adoptedStyleSheets.push(sheet2)

    sheet3 = new CSSStyleSheet()
    sheet3.replaceSync('div { color: green }')
    document.adoptedStyleSheets.push(sheet3)

    shouldBe("document.adoptedStyleSheets.length", "3");

    shouldBeFalse("delete document.adoptedStyleSheets.length;");

    shouldBeFalse("delete document.adoptedStyleSheets[0]");
    shouldBeFalse("delete document.adoptedStyleSheets[1]");
    shouldBeFalse("delete document.adoptedStyleSheets[3]");

    shouldBe("document.adoptedStyleSheets.length", "3");

    shouldBeTrue("delete document.adoptedStyleSheets[2]");
    shouldBe("document.adoptedStyleSheets.length", "2");
    shouldBe("document.adoptedStyleSheets[0]", "sheet1");
    shouldBe("document.adoptedStyleSheets[1]", "sheet2");
    shouldBeUndefined("document.adoptedStyleSheets[2]");

    shouldBeTrue("delete document.adoptedStyleSheets['1']");
    shouldBe("document.adoptedStyleSheets.length", "1");
    shouldBe("document.adoptedStyleSheets[0]", "sheet1");
    shouldBeUndefined("document.adoptedStyleSheets[1]");

    shouldBeTrue("delete document.adoptedStyleSheets[0]");
    shouldBe("document.adoptedStyleSheets.length", "0");
    shouldBeUndefined("document.adoptedStyleSheets[0]");

    evalAndLog("document.adoptedStyleSheets.foo = 1");
    shouldBeTrue("delete document.adoptedStyleSheets.foo;");
    shouldBeUndefined("document.adoptedStyleSheets.foo");
}

runTest();
</script>
</body>