gecko-dev/devtools/server/tests/browser/browser_stylesheets_getTextEmpty.js

/* Any copyright is dedicated to the Public Domain.
   http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

// Test that StyleSheetsActor.getText handles empty text correctly.

const CSS_CONTENT = "body { background-color: #f06; }";
const TEST_URI = `data:text/html;charset=utf-8,<style>${encodeURIComponent(
  CSS_CONTENT
)}</style>`;

add_task(async function() {
  const browser = await addTab(TEST_URI);
  const tab = gBrowser.getTabForBrowser(browser);

  const commands = await CommandsFactory.forTab(tab);
  await commands.targetCommand.startListening();
  const target = commands.targetCommand.targetFront;

  const styleSheetsFront = await target.getFront("stylesheets");
  ok(styleSheetsFront, "The StyleSheetsFront was created.");

  const sheets = [];
  await commands.resourceCommand.watchResources(
    [commands.resourceCommand.TYPES.STYLESHEET],
    {
      onAvailable: resources => sheets.push(...resources),
    }
  );
  is(sheets.length, 1, "watchResources returned the correct number of sheets");

  const { resourceId } = sheets[0];

  is(
    await getStyleSheetText(styleSheetsFront, resourceId),
    CSS_CONTENT,
    "The stylesheet has expected initial text"
  );
  info("Update stylesheet content via the styleSheetsFront");
  await styleSheetsFront.update(resourceId, "", false);
  is(
    await getStyleSheetText(styleSheetsFront, resourceId),
    "",
    "Stylesheet is now empty, as expected"
  );

  await commands.destroy();
});

async function getStyleSheetText(styleSheetsFront, resourceId) {
  const longStringFront = await styleSheetsFront.getText(resourceId);
  return longStringFront.string();
}