Implement common methods status(), read(), write()

tmt/steps/__init__.py

@@ -49,6 +49,9 @@ def __init__(self, data={}, plan=None, name=None):
             # Ensure that each config has a name
             if 'name' not in data and len(self.data) > 1:
                 raise GeneralError(f"Missing '{self}' name in '{self.plan}'.")
+        # Get or set the status
+        if self.status is None:
+            self.status('todo')
 
     @property
     def verbose(self):

tmt/steps/discover/__init__.py

@@ -34,9 +34,15 @@ def show(self):
 
     def go(self):
         """ Execute all steps """
+        # Nothing to do if already done
+        if self.status() == 'done':
+            return
+        # Go!
+        self.status('going')
         super(Discover, self).go()
         for step in self.steps:
             step.go()
+        self.status('done')
 
     def tests(self):
         """ Return a list of all tests """

tmt/utils.py

@@ -30,7 +30,7 @@ class Common(object):
     Takes care of command line context and workdir handling.
     """
 
-    # Command line context and workdir
+    # Command line context, workdir and status
     _context = None
     _workdir = None
 
@@ -72,6 +72,39 @@ def run(self, command, message=None):
         except subprocess.CalledProcessError as error:
             raise GeneralError(f"{message}\n{error}")
 
+    def read(self, path):
+        """ Read a file from the workdir """
+        path = os.path.join(self.workdir, path)
+        try:
+            with open(path) as data:
+                return data.read()
+        except OSError as error:
+            raise GeneralError(f"Failed to read '{path}'.\n{error}")
+
+    def write(self, path, data):
+        """ Write a file to the workdir """
+        path = os.path.join(self.workdir, path)
+        try:
+            with open(path, 'w') as target:
+                return target.write(data)
+        except OSError as error:
+            raise GeneralError(f"Failed to read '{path}'.\n{error}")
+
+    def status(self, status=None):
+        """ Get and set current status, store in workdir """
+        # Check for valid values
+        if status and status not in ['todo', 'done', 'going']:
+            raise GeneralError(f"Invalid status '{status}'.")
+        # Store status
+        if status:
+            self.write('status.txt', status + '\n')
+        # Read status
+        else:
+            try:
+                return self.read('status.txt').strip()
+            except GeneralError:
+                return None
+
     def _workdir_init(self, id_):
         """
         Initialize the work directory