add pytests for 'gpt guid' command in sandbox

Run unit tests for the 'gpt guid' command, making use of the block
device created by test/py/make_test_disk.py.  Remove this device at
the end of the tests.

Signed-off-by: Alison Chaiken <alison@peloton-tech.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

test/py/tests/test_gpt.py

@@ -0,0 +1,38 @@
+# Copyright (c) 2017 Alison Chaiken
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Test GPT manipulation commands.
+
+import os
+import pytest
+import u_boot_utils
+import make_test_disk
+
+"""
+These tests rely on a 4 MB block device called testdisk.raw
+which is automatically removed at the end of the tests.
+"""
+
+@pytest.mark.buildconfigspec('cmd_gpt')
+def test_gpt_guid(u_boot_console):
+    """Test the gpt guid command."""
+
+    if u_boot_console.config.buildconfig.get('config_cmd_gpt', 'n') != 'y':
+        pytest.skip('gpt command not supported')
+    make_test_disk.makeDisk()
+    u_boot_console.run_command('host bind 0 testdisk.raw')
+    output = u_boot_console.run_command('gpt guid host 0')
+    assert '375a56f7-d6c9-4e81-b5f0-09d41ca89efe' in output
+
+@pytest.mark.buildconfigspec('cmd_gpt')
+def test_gpt_save_guid(u_boot_console):
+    """Test the gpt guid command to save GUID into a string."""
+
+    if u_boot_console.config.buildconfig.get('config_cmd_gpt', 'n') != 'y':
+        pytest.skip('gpt command not supported')
+    u_boot_console.run_command('host bind 0 testdisk.raw')
+    output = u_boot_console.run_command('gpt guid host 0 newguid')
+    output = u_boot_console.run_command('printenv newguid')
+    assert '375a56f7-d6c9-4e81-b5f0-09d41ca89efe' in output
+    os.remove('testdisk.raw')