Method percy_snapshot

dash/testing/browser.py:137–222

percy_snapshot - visual test api shortcut to `percy_runner.snapshot`. It also combines the snapshot `name` with the Python version, args: - name: combined with the python version to give the final snapshot name - wait_for_callbacks: default False, whether to wait for

(
        self, name="", wait_for_callbacks=False, convert_canvases=False, widths=None
    )

            raise e

    def percy_snapshot(
        self, name="", wait_for_callbacks=False, convert_canvases=False, widths=None
    ):
        """percy_snapshot - visual test api shortcut to `percy_runner.snapshot`.
        It also combines the snapshot `name` with the Python version,
        args:
        - name: combined with the python version to give the final snapshot name
        - wait_for_callbacks: default False, whether to wait for Dash callbacks,
            after an extra second to ensure that any relevant callbacks have
            been initiated
        - convert_canvases: default False, whether to convert all canvas elements
            in the DOM into static images for percy to see. They will be restored
            after the snapshot is complete.
        - widths: a list of pixel widths for percy to render the page with. Note
            that this does not change the browser in which the DOM is constructed,
            so the width will only affect CSS, not JS-driven layout.
            Defaults to [1280]
        """
        if widths is None:
            widths = [1280]
        try:
            import asgiref  # pylint: disable=unused-import, import-outside-toplevel # noqa: F401, C0415

            name += "_async"
        except ImportError:
            pass

        logger.info("taking snapshot name => %s", name)
        try:
            if wait_for_callbacks:
                # the extra one second sleep adds safe margin in the context
                # of wait_for_callbacks
                time.sleep(1)
                until(self._wait_for_callbacks, timeout=40, poll=0.3)
        except TestingTimeoutError:
            # API will log the error but this TimeoutError should not block
            # the test execution to continue and it will still do a snapshot
            # as diff reference for the build run.
            logger.error(
                "wait_for_callbacks failed => status of invalid rqs %s",
                self.redux_state_rqs,
            )

        if convert_canvases:
            self.driver.execute_script(
                """
                const stash = window._canvasStash = [];
                Array.from(document.querySelectorAll('canvas')).forEach(c => {
                    const i = document.createElement('img');
                    i.src = c.toDataURL();
                    i.width = c.width;
                    i.height = c.height;
                    i.setAttribute('style', c.getAttribute('style'));
                    i.className = c.className;
                    i.setAttribute('data-canvasnum', stash.length);
                    stash.push(c);
                    c.parentElement.insertBefore(i, c);
                    c.parentElement.removeChild(c);