tests/acceptance: Add test of NeXTcube framebuffer using OCR

Add a test of the NeXTcube framebuffer using the Tesseract OCR
engine on a screenshot of the framebuffer device.

The test is very quick:

  $ avocado --show=app,console run tests/acceptance/machine_m68k_nextcube.py
  JOB ID     : 78844a92424cc495bd068c3874d542d1e20f24bc
  JOB LOG    : /home/phil/avocado/job-results/job-2019-08-13T13.16-78844a9/job.log
   (1/3) tests/acceptance/machine_m68k_nextcube.py:NextCubeMachine.test_bootrom_framebuffer_size: PASS (2.16 s)
   (2/3) tests/acceptance/machine_m68k_nextcube.py:NextCubeMachine.test_bootrom_framebuffer_ocr_with_tesseract_v3: -
  ue r pun Honl'flx ; 5‘ 55‘
  avg ncaaaaa 25 MHZ, memary jag m
  Backplane slat «a
  Ethernet address a a r a r3 2
  Memgry sackets aea canflqured far 16MB Darlly page made stMs but have 16MB page made stMs )nstalled
  Memgry sackets a and 1 canflqured far 16MB Darlly page made stMs but have 16MB page made stMs )nstalled
  [...]
  Yestlnq the rpu, 5::
  system test raneg Errar egge 51
  Egg: cammand
  Default pggc devlce nut fauna
  NEXY>I
  PASS (2.64 s)
   (3/3) tests/acceptance/machine_m68k_nextcube.py:NextCubeMachine.test_bootrom_framebuffer_ocr_with_tesseract_v4: SKIP: tesseract v4 OCR tool not available
  RESULTS    : PASS 2 | ERROR 0 | FAIL 0 | SKIP 1 | WARN 0 | INTERRUPT 0 | CANCEL 0
  JOB TIME   : 5.35 s

Documentation on how to install tesseract:
  https://github.com/tesseract-ocr/tesseract/wiki#installationSigned-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20190813134921.30602-2-philmd@redhat.com>
Signed-off-by: NThomas Huth <huth@tuxfamily.org>

tests/acceptance/machine_m68k_nextcube.py

+# Functional test that boots a VM and run OCR on the framebuffer
+#
+# Copyright (c) Philippe Mathieu-Daudé <f4bug@amsat.org>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or
+# later.  See the COPYING file in the top-level directory.
+
+import os
+import re
+import time
+import logging
+import distutils.spawn
+
+from avocado_qemu import Test
+from avocado import skipUnless
+from avocado.utils import process
+from avocado.utils.path import find_command, CmdNotFoundError
+
+PIL_AVAILABLE = True
+try:
+    from PIL import Image
+except ImportError:
+    PIL_AVAILABLE = False
+
+
+def tesseract_available(expected_version):
+    try:
+        find_command('tesseract')
+    except CmdNotFoundError:
+        return False
+    res = process.run('tesseract --version')
+    try:
+        version = res.stdout_text.split()[1]
+    except IndexError:
+        version = res.stderr_text.split()[1]
+    return int(version.split('.')[0]) == expected_version
+
+    match = re.match(r'tesseract\s(\d)', res)
+    if match is None:
+        return False
+    # now this is guaranteed to be a digit
+    return int(match.groups()[0]) == expected_version
+
+
+class NextCubeMachine(Test):
+
+    timeout = 15
+
+    def check_bootrom_framebuffer(self, screenshot_path):
+        rom_url = ('http://www.nextcomputers.org/NeXTfiles/Software/ROM_Files/'
+                   '68040_Non-Turbo_Chipset/Rev_2.5_v66.BIN')
+        rom_hash = 'b3534796abae238a0111299fc406a9349f7fee24'
+        rom_path = self.fetch_asset(rom_url, asset_hash=rom_hash)
+
+        self.vm.set_machine('next-cube')
+        self.vm.add_args('-bios', rom_path)
+        self.vm.launch()
+
+        self.log.info('VM launched, waiting for display')
+        # TODO: Use avocado.utils.wait.wait_for to catch the
+        #       'displaysurface_create 1120x832' trace-event.
+        time.sleep(2)
+
+        self.vm.command('human-monitor-command',
+                        command_line='screendump %s' % screenshot_path)
+
+    @skipUnless(PIL_AVAILABLE, 'Python PIL not installed')
+    def test_bootrom_framebuffer_size(self):
+        """
+        :avocado: tags=arch:m68k
+        :avocado: tags=machine:next_cube
+        :avocado: tags=device:framebuffer
+        """
+        screenshot_path = os.path.join(self.workdir, "dump.png")
+        self.check_bootrom_framebuffer(screenshot_path)
+
+        width, height = Image.open(screenshot_path).size
+        self.assertEqual(width, 1120)
+        self.assertEqual(height, 832)
+
+    @skipUnless(tesseract_available(3), 'tesseract v3 OCR tool not available')
+    def test_bootrom_framebuffer_ocr_with_tesseract_v3(self):
+        """
+        :avocado: tags=arch:m68k
+        :avocado: tags=machine:next_cube
+        :avocado: tags=device:framebuffer
+        """
+        screenshot_path = os.path.join(self.workdir, "dump.png")
+        self.check_bootrom_framebuffer(screenshot_path)
+
+        console_logger = logging.getLogger('console')
+        text = process.run("tesseract %s stdout" % screenshot_path).stdout_text
+        for line in text.split('\n'):
+            if len(line):
+                console_logger.debug(line)
+        self.assertIn('Backplane', text)
+        self.assertIn('Ethernet address', text)
+
+    # Tesseract 4 adds a new OCR engine based on LSTM neural networks. The
+    # new version is faster and more accurate than version 3. The drawback is
+    # that it is still alpha-level software.
+    @skipUnless(tesseract_available(4), 'tesseract v4 OCR tool not available')
+    def test_bootrom_framebuffer_ocr_with_tesseract_v4(self):
+        """
+        :avocado: tags=arch:m68k
+        :avocado: tags=machine:next_cube
+        :avocado: tags=device:framebuffer
+        """
+        screenshot_path = os.path.join(self.workdir, "dump.png")
+        self.check_bootrom_framebuffer(screenshot_path)
+
+        console_logger = logging.getLogger('console')
+        proc = process.run("tesseract --oem 1 %s stdout" % screenshot_path)
+        text = proc.stdout_text
+        for line in text.split('\n'):
+            if len(line):
+                console_logger.debug(line)
+        self.assertIn('Testing the FPU, SCC', text)
+        self.assertIn('System test failed. Error code 51', text)
+        self.assertIn('Boot command', text)
+        self.assertIn('Next>', text)