More efficient and reliable tracking of prerequisites. (#67)

* ensure we are correctly tracking prereq and other sections (note this wasn't a problem before, adding merely to catch unexpected edge cases)

* if prereq step is empty record as a description line rather than a prereq

* we must have a source_file_dir, otherwise we don't know where to build relative paths from

* typo

* more descriptive comment

* incorrect timeout option for curl, tests were passing but there was an extra attempt to connect to a url of '-connect-timeout'

* Add a check for whether a prereq has already been run or not. This will make execution faster when a prereq comes from two different parts of a test plan (for example)

* simpler way of tracking prereq validation - which happens to work too!

* Merge from master

cli.py

@@ -300,7 +300,7 @@ to select it) and a title (to be displayed).
         if command.startswith("xdg-open "):
             self.warning("Since you are running in headless CLI mode it is not possible to execute xdg-open commands.")
 
-            command = "curl -I " + command[9:] + " -connect-timeout 90"
+            command = "curl -I " + command[9:] + " --connect-timeout 90"
             
             self.warning("Converting to `" + command + "`")
             self.warning("Note that this may break tests.")
@@ -319,7 +319,7 @@ to select it) and a title (to be displayed).
 
     def expand_vars(self, command):
         """Expand the variables in the supplied command by replacing them
-        with the value they carry in the Environment."""
+        with the value they carry in the Environment. This is used by some special commands because the shell doesn't expand them (e.g. copying a $URL into a browser window using xdg-open)"""
 
         self.log("debug", "Expanding vars in " + command)
         var_pattern = re.compile(".*?(?<=\$)\(?{?(\w*)(?=[\W|\$|\s|\\\"]?)\)?(?!\$).*")

demo.py

@@ -55,7 +55,8 @@ class Demo(object):
         self.is_prerequisite = is_prerequisite
         self.output_format = output_format
         self.all_results = []
-
+        self.completed_validation_steps = []
+        
     def set_script_dir(self, script_dir, base_dir = None):
         if base_dir is not None and not base_dir.endswith(os.sep):
             base_dir += os.sep
@@ -498,7 +499,7 @@ logs throughout execution."""
         actual_results = ""
         failed_tests = 0
         passed_tests = 0
-        in_prerequisites = False
+        done_prerequisites = False
         in_validation = False
         executed_code_in_this_section = False
         next_steps = []
@@ -531,16 +532,12 @@ logs throughout execution."""
                 expected_results = ""
                 actual_results = ""
                 in_results = False
-            elif line["type"] == "prerequisite" and not in_prerequisites:
-                self.ui.log("debug", "Entering prerequisites")
-                in_prerequisites = True
-            elif line["type"] != "prerequisites" and len(line["text"]) > 0 and in_prerequisites:
-                self.ui.log("debug", "Got all prerequisites")
+            elif line["type"] == "prerequisite" and not done_prerequisites:
+                self.ui.heading(line["text"])
                 self.check_prerequisites(lines, source_file_directory)
+                done_prerequisites = True
                 if self.is_prep_only:
                     return failed_tests, passed_tests
-                in_prerequisites = False
-                self.ui.heading(line["text"])
             elif line["type"] == "executable":
                 if line["text"].strip() == "":
                     break
@@ -610,6 +607,7 @@ logs throughout execution."""
                             href = href + "README.md"
                         step["href"] = href
                         steps.append(step)
+                        self.ui.log("debug", "Found prereq: " + str(step))
 
         for step in steps:
             path, filename = os.path.split(step["href"])
@@ -622,6 +620,12 @@ logs throughout execution."""
             else:
                 new_dir = path
 
+            new_dir = os.path.abspath(new_dir)
+            full_path = os.path.join(new_dir, filename)
+            if full_path in self.completed_validation_steps:
+                self.ui.log("debug", "Already validated / executed script in  " + full_path)
+                return
+            
             self.ui.new_para()
 
             self.ui.log("debug", "Execute prerequisite step in " + filename + " in " + new_dir)
@@ -631,6 +635,8 @@ logs throughout execution."""
             demo.run_if_validation_fails(self.mode)
             self.ui.get_shell().run_command("popd ") # set_ui runs pushd
             self.ui.set_demo(self) # demo.set_ui(...) assigns new demo to ui, this reverts after prereq execution
+
+            self.completed_validation_steps.append(full_path)
             self.ui.check_for_interactive_command()
             
     def run_if_validation_fails(self, mode = None):

demo_scripts/test/README.md

@@ -37,6 +37,11 @@ test files. The [prerequisite test script](./prerequisites/README.md)
 validates whether the file exists and, if it doesn't it will execute
 and create it.
 
+Each [prerequisite](./prerequisites/README.md) will only be run once,
+so even though this partucular prereq appears twice it will only
+execute once. This is important when building multi-part tutorials/
+demos where a prereq may be included in more than one part.
+
 ## Validate prerequisite ran
 
 The prerequisite script should have run and created a `prereq_ran`

environment.py

@@ -116,7 +116,7 @@ class Environment(object):
         
     def process_env(self, new_env):
         """
-        Takes an environmetn definition and processes it for use.
+        Takes an environment definition and processes it for use.
         For example, expand '~' to home directory.
         """
         for key in new_env: