implement 'fortress' unit test mode

- implement navigation function for loading a fortress from the title
  screen (requires a fortress save to be ready in region1/).
- ensure we don't try repeatedly to enter a mode that we can't reach
  (such as getting back to the title screen from fortress mode). failing
  to enter the mode once will skip all remaining tests in that mode.

ci/test.lua

@@ -66,8 +66,6 @@ local TestStatus = {
     FAILED = 'failed',
 }
 
-local VALID_MODES = utils.invert{'none', 'title', 'fortress'}
-
 local function delay(frames)
     frames = frames or 1
     script.sleep(frames, 'frames')
@@ -116,29 +114,87 @@ end
 test_envvars.require = clean_require
 test_envvars.reqscript = clean_reqscript
 
+local function is_title_screen(scr)
+    scr = scr or dfhack.gui.getCurViewscreen()
+    return df.viewscreen_titlest:is_instance(scr)
+end
+
+-- This only handles pre-fortress-load screens. It will time out if the player
+-- has already loaded a fortress or is in any screen that can't get to the title
+-- screen by sending ESC keys.
 local function ensure_title_screen()
-    if df.viewscreen_titlest:is_instance(dfhack.gui.getCurViewscreen()) then
+    for i = 1, 100 do
+        local scr = dfhack.gui.getCurViewscreen()
+        if is_title_screen(scr) then
+            print('Found title screen')
+            return
+        end
+        scr:feed_key(df.interface_key.LEAVESCREEN)
+        delay(10)
+        if i % 10 == 0 then print('Looking for title screen...') end
+    end
+    qerror(string.format('Could not find title screen (timed out at %s)',
+                         dfhack.gui.getCurFocus(true)))
+end
+
+local function is_fortress(focus_string)
+    focus_string = focus_string or dfhack.gui.getCurFocus(true)
+    return focus_string == 'dwarfmode/Default'
+end
+
+-- Requires that a fortress game is already loaded or is ready to be loaded via
+-- the "Continue Playing" option in the title screen. Otherwise the function
+-- will time out and/or exit with error.
+local function ensure_fortress()
+    local focus_string = dfhack.gui.getCurFocus(true)
+    for screen_timeout = 1,10 do
+        if is_fortress(focus_string) then
+            print('Loaded fortress map')
+            -- pause the game (if it's not already paused)
+            dfhack.gui.resetDwarfmodeView(true)
             return
         end
-    print('Looking for title screen...')
-    for i = 0, 100 do
         local scr = dfhack.gui.getCurViewscreen()
-        if df.viewscreen_titlest:is_instance(scr) then
-            print('Found title screen')
-            break
-        else
+        if focus_string == 'title' then
+            scr:feed_key(df.interface_key.SELECT)
+            scr:feed_key(df.interface_key.SELECT)
+        elseif focus_string == 'dfhack/lua/load_screen' or
+                focus_string == 'dfhack/lua' then
+            scr:feed_key(df.interface_key.SELECT)
+        elseif focus_string == 'new_region' or
+                focus_string == 'adopt_region' then
+            qerror('Please ensure a fortress save exists in region1/')
+        elseif focus_string ~= 'loadgame' then
+            -- if we're not actively loading a game, assume we're in
+            -- a loaded fortress, but in some subscreen
             scr:feed_key(df.interface_key.LEAVESCREEN)
+        end
+        -- wait for active screen to change
+        local prev_focus_string = focus_string
+        for frame_timeout = 1,100 do
             delay(10)
+            focus_string = dfhack.gui.getCurFocus(true)
+            if focus_string ~= prev_focus_string then
+                goto next_screen
+            end
+            if frame_timeout % 10 == 0 then
+                print(string.format(
+                    'Loading fortress (currently at screen: %s)',
+                    focus_string))
             end
         end
-    if not df.viewscreen_titlest:is_instance(dfhack.gui.getCurViewscreen()) then
-        error('Could not find title screen')
+        print('Timed out waiting for screen to change')
+        break
+        ::next_screen::
     end
+    qerror(string.format('Could not load fortress (timed out at %s)',
+                         focus_string))
 end
 
-local MODE_NAVIGATE_FNS = {
-    none = function() end,
-    title = ensure_title_screen,
+local MODES = {
+    none = {order=1, detect=function() return true end},
+    title = {order=2, detect=is_title_screen, navigate=ensure_title_screen},
+    fortress = {order=3, detect=is_fortress, navigate=ensure_fortress},
 }
 
 local function load_test_config(config_file)
@@ -266,7 +322,7 @@ local function load_tests(file, tests)
             dfhack.printerr('Error when running file: ' .. tostring(err))
             return false
         else
-            if not VALID_MODES[env.config.mode] then
+            if not MODES[env.config.mode] then
                 dfhack.printerr('Invalid config.mode: ' .. tostring(env.config.mode))
                 return false
             end
@@ -290,10 +346,9 @@ local function sort_tests(tests)
     local test_index = utils.invert(tests)
     table.sort(tests, function(a, b)
         if a.config.mode ~= b.config.mode then
-            return VALID_MODES[a.config.mode] < VALID_MODES[b.config.mode]
-        else
-            return test_index[a] < test_index[b]
+            return MODES[a.config.mode].order < MODES[b.config.mode].order
         end
+        return test_index[a] < test_index[b]
     end)
 end
 
@@ -418,9 +473,19 @@ end
 local function run_tests(tests, status, counts)
     print(('Running %d tests'):format(#tests))
     for _, test in pairs(tests) do
-        MODE_NAVIGATE_FNS[test.config.mode]()
-        local passed = run_test(test, status, counts)
-        status[test.full_name] = passed and TestStatus.PASSED or TestStatus.FAILED
+        status[test.full_name] = TestStatus.FAILED
+        if MODES[test.config.mode].failed then goto skip end
+        if not MODES[test.config.mode].detect() then
+            local ok, err = pcall(MODES[test.config.mode].navigate)
+            if not ok then
+                MODES[test.config.mode].failed = true
+                dfhack.printerr(tostring(err))
+                goto skip
+            end
+        end
+        status[test.full_name] = run_test(test, status, counts) and
+                TestStatus.PASSED or TestStatus.FAILED
+        ::skip::
         save_test_status(status)
     end