Add tests for the new content API. This includes tests for root.content(),

screen.content, and client.content. Run with TESTS_SCREEN_SIZE set equal
to 1280x800. This test suite will be expanded once the more user
friendly awful.screenshot API is merged.

Signed off: Brian Sobulefsky <brian.sobulefsky@protonmail.com>

tests/test-screenshot.lua

@@ -0,0 +1,164 @@
+-- This test suite tests the various screenshot related APIs.
+--
+-- Credit: https://www.reddit.com/r/awesomewm/comments/i6nf7z/need_help_writing_a_color_picker_widget_using_lgi/
+local wibox = require("wibox")
+local spawn = require("awful.spawn")
+local gsurface = require("gears.surface")
+local lgi = require 'lgi'
+local cairo = lgi.cairo
+local gdk = lgi.Gdk
+
+-- Dummy blue client for the client.content test
+-- the lua_executable portion may need to get ironed out. I need to specify 5.3
+local lua_executable = os.getenv("LUA")
+if lua_executable == nil or lua_executable == "" then
+    lua_executable = "lua5.3"
+end
+local client_dim = 250
+local tiny_client_code_template = [[
+local Gtk = require('lgi').Gtk
+local Gdk = require('lgi').Gdk
+local class = 'client'
+window = Gtk.Window {default_width=%d, default_height=%d, title='title'}
+window:set_wmclass(class, class)
+window:override_background_color(0,
+    Gdk.RGBA({red = 0, green = 0, blue = 1, alpha = 1}))
+window:show_all()
+Gtk:main{...}
+]]
+local tiny_client = { lua_executable, "-e", string.format(
+                          tiny_client_code_template, client_dim, client_dim)}
+
+-- how to make a GTK window using LGI
+
+-- Split in the screen into 2 distict screens.
+screen[1]:split()
+
+-- Add a green wibox on screen 1 at (100, 100)
+wibox {
+    bg      = "#00ff00",
+    visible = true,
+    width   = 100,
+    height  = 100,
+    x       = 100,
+    y       = 100,
+}
+
+local corners = {}
+
+-- Add red squares at 1 pixel away from each screen corners.
+for s in screen do
+    -- Top left
+    table.insert(corners, {
+        x = s.geometry.x + 1,
+        y = s.geometry.y + 1,
+    })
+
+    -- Top right
+    table.insert(corners, {
+        x = s.geometry.x + s.geometry.width - 11,
+        y = s.geometry.y + 1,
+    })
+
+    -- Bottom left
+    table.insert(corners, {
+        x = s.geometry.x + 1,
+        y = s.geometry.y + s.geometry.height - 11,
+    })
+
+    -- Bottom right
+    table.insert(corners, {
+        x = s.geometry.x + s.geometry.width - 11,
+        y = s.geometry.y + s.geometry.height - 11,
+    })
+
+end
+
+-- Make 10x10 wibox in each corner to eliminate any geometry errors
+for _, corner in ipairs(corners) do
+    corner.bg = "#ff0000"
+    corner.visible = true
+    corner.width = 10
+    corner.height = 10
+
+    wibox(corner)
+end
+
+local function copy_to_image_surface(content, w, h)
+    local sur = gsurface(content)
+
+    local img = cairo.ImageSurface(cairo.Format.RGB24, w, h)
+    local cr = cairo.Context(img)
+
+    cr:set_source_surface(sur)
+    cr:paint()
+    img:finish()
+
+    return img
+end
+
+local function get_pixel(img, x, y)
+    local bytes = gdk.pixbuf_get_from_surface(img, x, y, 1, 1):get_pixels()
+    return "#" .. bytes:gsub('.', function(c) return ('%02x'):format(c:byte()) end)
+end
+
+local steps = {}
+
+-- Check the whole root window.
+table.insert(steps, function()
+    local img = copy_to_image_surface(root.content(), root.size())
+    local root_width, root_height = root.size()
+
+    if get_pixel(img, 100, 100) ~= "#00ff00" then return end
+    if get_pixel(img, 2, 2) ~= "#ff0000" then return end
+
+    assert(get_pixel(img, 100, 100) == "#00ff00")
+    assert(get_pixel(img, 199, 199) == "#00ff00")
+    assert(get_pixel(img, 201, 201) ~= "#00ff00")
+
+    assert(get_pixel(img, 2, 2) == "#ff0000")
+    assert(get_pixel(img, root_width - 2, 2) == "#ff0000")
+    assert(get_pixel(img, 2, root_height - 2) == "#ff0000")
+    assert(get_pixel(img, root_width - 2, root_height - 2) == "#ff0000")
+
+    return true
+end)
+
+-- Check the screen.content
+table.insert(steps, function()
+    for s in screen do
+
+      local geo = s.geometry
+      local img = copy_to_image_surface(s.content, geo.width, geo.height)
+
+      assert(get_pixel(img, geo.x + 4, geo.y + 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + geo.width - 4, geo.y + 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + 4, geo.y + geo.height - 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + geo.width - 4, geo.y + geo.height - 4) == "#ff0000")
+
+    end
+
+    -- Spawn for the client.content test
+    assert(#client.get() == 0)
+    spawn(tiny_client)
+
+    return true
+end)
+
+-- Check the client.content
+table.insert(steps, function()
+    if #client.get() ~= 1 then return end
+    local c = client.get()[1]
+    local geo = c:geometry()
+    local img = copy_to_image_surface(c.content, geo.width, geo.height)
+
+    if get_pixel(img, math.floor(geo.width / 2), math.floor(geo.height / 2)) ~= "#0000ff" then
+        return
+    end
+
+    awesome.kill(c.pid, 9)
+
+    return true
+end)
+
+require("_runner").run_steps(steps)