test/py: add skip marker for reliance on tools

Some tests use external tools (executables) during their operation. Add
a test.py mark to indicate this. This allows those tests to be skipped if
the required tool is not present.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/test/py/conftest.py b/test/py/conftest.py
index e2fc7fd..6e66a48 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -457,6 +457,34 @@
         if not ubconfig.buildconfig.get('config_' + option.lower(), None):
             pytest.skip('.config feature "%s" not enabled' % option.lower())
 
+def tool_is_in_path(tool):
+    for path in os.environ["PATH"].split(os.pathsep):
+        fn = os.path.join(path, tool)
+        if os.path.isfile(fn) and os.access(fn, os.X_OK):
+            return True
+    return False
+
+def setup_requiredtool(item):
+    """Process any 'requiredtool' marker for a test.
+
+    Such a marker lists some external tool (binary, executable, application)
+    that the test requires. If tests are being executed on a system that
+    doesn't have the required tool, the test is marked to be skipped.
+
+    Args:
+        item: The pytest test item.
+
+    Returns:
+        Nothing.
+    """
+
+    mark = item.get_marker('requiredtool')
+    if not mark:
+        return
+    for tool in mark.args:
+        if not tool_is_in_path(tool):
+            pytest.skip('tool "%s" not in $PATH' % tool)
+
 def start_test_section(item):
     anchors[item.name] = log.start_section(item.name)
 
@@ -476,6 +504,7 @@
     start_test_section(item)
     setup_boardspec(item)
     setup_buildconfigspec(item)
+    setup_requiredtool(item)
 
 def pytest_runtest_protocol(item, nextitem):
     """pytest hook: Called to execute a test.
diff --git a/test/py/tests/test_dfu.py b/test/py/tests/test_dfu.py
index fba67d5..8f6877c 100644
--- a/test/py/tests/test_dfu.py
+++ b/test/py/tests/test_dfu.py
@@ -113,6 +113,7 @@
 first_usb_dev_port = None
 
 @pytest.mark.buildconfigspec('cmd_dfu')
+@pytest.mark.requiredtool('dfu-util')
 def test_dfu(u_boot_console, env__usb_dev_port, env__dfu_config):
     """Test the "dfu" command; the host system must be able to enumerate a USB
     device when "dfu" is running, various DFU transfers are tested, and the
diff --git a/test/py/tests/test_fit.py b/test/py/tests/test_fit.py
index 7e6b96d..4b32bb1 100755
--- a/test/py/tests/test_fit.py
+++ b/test/py/tests/test_fit.py
@@ -111,6 +111,7 @@
 
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('fit_signature')
+@pytest.mark.requiredtool('dtc')
 def test_fit(u_boot_console):
     def make_fname(leaf):
         """Make a temporary filename
diff --git a/test/py/tests/test_gpt.py b/test/py/tests/test_gpt.py
index e2bbd08..ec25fbb 100644
--- a/test/py/tests/test_gpt.py
+++ b/test/py/tests/test_gpt.py
@@ -38,15 +38,14 @@
             fd = os.open(self.path, os.O_RDWR | os.O_CREAT)
             os.ftruncate(fd, 4194304)
             os.close(fd)
-            sgdisk = '/sbin/sgdisk'
-            cmd = (sgdisk, '-U', '375a56f7-d6c9-4e81-b5f0-09d41ca89efe',
+            cmd = ('sgdisk', '-U', '375a56f7-d6c9-4e81-b5f0-09d41ca89efe',
                 self.path)
             u_boot_utils.run_and_log(u_boot_console, cmd)
-            cmd = (sgdisk, '--new=1:2048:2560', self.path)
+            cmd = ('sgdisk', '--new=1:2048:2560', self.path)
             u_boot_utils.run_and_log(u_boot_console, cmd)
-            cmd = (sgdisk, '--new=2:4096:4608', self.path)
+            cmd = ('sgdisk', '--new=2:4096:4608', self.path)
             u_boot_utils.run_and_log(u_boot_console, cmd)
-            cmd = (sgdisk, '-l', self.path)
+            cmd = ('sgdisk', '-l', self.path)
             u_boot_utils.run_and_log(u_boot_console, cmd)
 
 gtdi = None
@@ -64,6 +63,7 @@
 
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('cmd_gpt')
+@pytest.mark.requiredtool('sgdisk')
 def test_gpt_guid(state_disk_image, u_boot_console):
     """Test the gpt guid command."""
 
@@ -73,6 +73,7 @@
 
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('cmd_gpt')
+@pytest.mark.requiredtool('sgdisk')
 def test_gpt_save_guid(state_disk_image, u_boot_console):
     """Test the gpt guid command to save GUID into a string."""
 
@@ -86,6 +87,7 @@
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('cmd_gpt')
 @pytest.mark.buildconfigspec('cmd_gpt_rename')
+@pytest.mark.requiredtool('sgdisk')
 def test_gpt_rename_partition(state_disk_image, u_boot_console):
     """Test the gpt rename command to write partition names."""
 
@@ -101,6 +103,7 @@
 @pytest.mark.buildconfigspec('cmd_gpt')
 @pytest.mark.buildconfigspec('cmd_gpt_rename')
 @pytest.mark.buildconfigspec('cmd_part')
+@pytest.mark.requiredtool('sgdisk')
 def test_gpt_swap_partitions(state_disk_image, u_boot_console):
     """Test the gpt swap command to exchange two partition names."""
 
diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py
index 6e62820..c4da79d 100644
--- a/test/py/tests/test_vboot.py
+++ b/test/py/tests/test_vboot.py
@@ -31,6 +31,10 @@
 
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('fit_signature')
+@pytest.mark.requiredtool('dtc')
+@pytest.mark.requiredtool('fdtget')
+@pytest.mark.requiredtool('fdtput')
+@pytest.mark.requiredtool('openssl')
 def test_vboot(u_boot_console):
     """Test verified boot signing with mkimage and verification with 'bootm'.