This vastly simplifies our code, and saves us the ugly math.
While at it, establish that a TestDriver must have a white background,
which is already satisfied by both existing implementations.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
The e2e app now splits the window into four rectangles and paints them
differently.
The first advantage is that we now test that we see the entire Gio app.
Before, with a solid background color, we could be seeing a small part
of the window and we wouldn't tell the difference.
The second advantage is that we test more colors. In particular, the
fourth color includes a different alpha value, which renders the same on
JS and X11.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Now we implement the "red background" end-to-end test exactly once.
While at it, start using a 800x600 window size, which is a bit more
realistic than 600x600, and will catch if we got either dimension wrong.
The interface only has two methods for now, but it will be expanded in
the future to also support input such as clicks.
Keeping state in the test driver, such as a context or a connection, is
a bit awkward but necessary so that we don't have to repeat arguments
over and over. The same applies to testing.T.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>