Improve plug-in loader

Always load plug-ins in the specified order.
Simplify and test the new documented bootstrap mechanism.

Author: Cito

docs/appdev.rst

@@ -366,16 +366,12 @@ Some IDEs like PyCharm can also debug remote processes. This could be useful to
 Bootstrap Webware from Command line
 -----------------------------------
 
-You may be in a situation where you want to execute some part of your Webware app from the command line, for example to implement a cron job or 
-maintenance script.  In these situations you probably don't want to instantiate a full-fledged `Application` -- some of the downsides are that doing so
-would cause standard output and standard error to be redirected to the log file, and that it sets up the session sweeper, task manager, etc. 
-But you may still need access to plugins such as MiscUtils, MiddleKit, which you may not be able to import directly.
+You may be in a situation where you want to execute some part of your Webware applicaton from the command line, for example to implement a cron job or maintenance script. In these situations you probably don't want to instantiate a full-fledged `Application` -- some of the downsides are that doing so would cause standard output and standard error to be redirected to the log file, and that it sets up the session sweeper, task manager, etc. But you may still need access to plugins such as MiscUtils, MiddleKit, which you may not be able to import directly.
 
 Here is a lightweight approach which allows you to bootstrap Webware and plugins::
 
    import webware
-   webware.add_to_python_path()
-   webware.load_plugins('/your/app/directory')
+   app = webware.mockAppWithPlugins()
 
    # now plugins are available...
    import MiscUtils

webware/Application.py

@@ -99,6 +99,7 @@
     OutputEncoding='utf-8',
     PlugIns=['MiscUtils', 'WebUtils', 'TaskKit', 'UserKit', 'PSP'],
     PrintConfigAtStartUp=True,
+    PrintPlugIns=True,
     ReloadServletClasses=False,
     ReportRPCExceptionsInWebware=True,
     ResponseBufferSize=8 * 1024,  # 8 kBytes

webware/MockApplication.py

@@ -3,7 +3,7 @@
 from ConfigurableForServerSidePath import ConfigurableForServerSidePath
 
 
-class MockImportManager(object):
+class MockImportManager:
 
     def recordFile(self, filename, isfile=None):
         pass
@@ -12,6 +12,7 @@ def recordFile(self, filename, isfile=None):
 defaultConfig = dict(
     CacheDir='Cache',
     PlugIns=['MiscUtils', 'WebUtils', 'TaskKit', 'UserKit', 'PSP'],
+    PrintPlugIns=False
 )
 
 
@@ -30,11 +31,11 @@ def __init__(self, path=None, settings=None, development=None):
         if development is None:
             development = bool(os.environ.get('WEBWARE_DEVELOPMENT'))
         self._development = development
-
-        appConfig = self.config()  # get and cache the configuration
+        appConfig = self.config()
         if settings:
             appConfig.update(settings)
-        self._cacheDir = self.serverSidePath(self.setting('CacheDir') or 'Cache')
+        self._cacheDir = self.serverSidePath(
+            self.setting('CacheDir') or 'Cache')
         from MiscUtils.PropertiesObject import PropertiesObject
         props = PropertiesObject(os.path.join(
             self._webwarePath, 'Properties.py'))
@@ -64,7 +65,7 @@ def serverSidePath(self, path=None):
                 os.path.join(self._serverSidePath, path))
         return self._serverSidePath
 
-    def hasContext(self, context):
+    def hasContext(self, _name):
         return False
 
     def addServletFactory(self, factory):

webware/PlugInLoader.py

@@ -3,11 +3,10 @@
 from PlugIn import PlugIn
 
 
-class PlugInLoader(object):
+class PlugInLoader:
 
     def __init__(self, app):
         self.app = app
-        self._plugIns = {}
 
     def loadPlugIn(self, name, module, verbose=True):
         """Load and return the given plug-in.
@@ -29,32 +28,43 @@ def loadPlugIn(self, name, module, verbose=True):
             raise
         return plugIn
 
-    def loadPlugIns(self, plugInNames, verbose=True):
+    def loadPlugIns(self, plugInNames=None, verbose=None):
         """Load all plug-ins.
 
         A plug-in allows you to extend the functionality of Webware without
         necessarily having to modify its source. Plug-ins are loaded by
         Application at startup time, just before listening for requests.
         See the docs in `PlugIn` for more info.
         """
-        plugInNames = set(plugInNames)
-        plugInNames.add('Webware')
-        plugIns = [
-            (entry_point.name, entry_point.load())
-            for entry_point
-            in pkg_resources.iter_entry_points('webware.plugins')
-            if entry_point.name in plugInNames
-        ]
+        if plugInNames is None:
+            plugInNames = self.app.setting('PlugIns')
+        if verbose is None:
+            verbose = self.app.setting('PrintPlugIns')
 
         if verbose:
-            print('Plug-ins list:', ', '.join(
-                name for name, _module in plugIns if name != 'Webware'))
+            print('Plug-ins list:', ', '.join(plugInNames))
 
-        # Now that we have our plug-in list, load them...
-        for name, module in plugIns:
+        entryPoints = {
+            entry_point.name: entry_point for entry_point
+            in pkg_resources.iter_entry_points('webware.plugins')}
+
+        plugIns = {}
+        for name in plugInNames:
+            if name in plugIns:
+                if verbose:
+                    print(f'Plug-in {name} has already been loaded.')
+                    continue
+            entry_point = entryPoints.get(name)
+            if not entry_point:
+                if verbose:
+                    print(f'Plug-in {name} has not entry point.')
+                    continue
+            module = entry_point.load()
             plugIn = self.loadPlugIn(name, module, verbose=verbose)
             if plugIn:
-                self._plugIns[name] = plugIn
+                plugIns[name] = plugIn
+
         if verbose:
             print()
-        return self._plugIns
+
+        return plugIns

webware/Scripts/WSGIScript.py

@@ -21,9 +21,7 @@
     os.chdir(workDir)
 
 import webware
-webwarePath = webware.__path__[0]
-if webwarePath not in sys.path:
-    sys.path.insert(0, webwarePath)
+webware.addToSearchPath()
 
 from Application import Application
 

webware/Tests/TestEndToEnd/TestServer.py

@@ -33,13 +33,13 @@
 Loading context: Examples at .+Examples
 Loading context: Admin at .+Admin
 Loading context: Testing at .+Testing
-Plug-ins list: MiscUtils, PSP, TaskKit, UserKit, WebUtils
+Plug-ins list: MiscUtils, WebUtils, TaskKit, UserKit, PSP
 Loading plug-in: MiscUtils at .+MiscUtils
-Loading plug-in: PSP at .+PSP
-Loading context: PSP/Examples at .+Examples
+Loading plug-in: WebUtils at .+WebUtils
 Loading plug-in: TaskKit at .+TaskKit
 Loading plug-in: UserKit at .+UserKit
-Loading plug-in: WebUtils at .+WebUtils
+Loading plug-in: PSP at .+PSP
+Loading context: PSP/Examples at .+Examples
 
 Waitress serving Webware application...
 Serving on http://.+:8080

webware/Tests/TestMocking.py

@@ -0,0 +1,40 @@
+"""Test Webware Mock Environment"""
+
+import io
+import sys
+import unittest
+
+import webware
+
+
+class TestMocking(unittest.TestCase):
+
+    def setUp(self):
+        self.sysPath = sys.path
+        self.webwarePath = webware.__path__[0]
+        sys.path = [path for path in sys.path if path != self.webwarePath]
+        self.sysStdout = sys.stdout
+        sys.stdout = io.StringIO()
+        self.getOutput = sys.stdout.getvalue
+
+    def tearDown(self):
+        sys.stdout = self.sysStdout
+        sys.path = self.sysPath
+
+    def testAddToSearchPath(self):
+        assert self.webwarePath not in sys.path
+        webware.addToSearchPath()
+        assert self.webwarePath in sys.path
+
+    def testLoadPlugins(self):
+        webware.addToSearchPath()
+        app = webware.mockAppWithPlugins(
+            self.webwarePath, settings={'PrintPlugIns': True})
+        self.assertEqual(app.__class__.__name__, 'MockApplication')
+        output = self.getOutput().splitlines()
+        output = [line.split(' at ', 1)[0] for line in output]
+        self.assertEqual(output, [
+            'Plug-ins list: MiscUtils, WebUtils, TaskKit, UserKit, PSP',
+            'Loading plug-in: MiscUtils', 'Loading plug-in: WebUtils',
+            'Loading plug-in: TaskKit', 'Loading plug-in: UserKit',
+            'Loading plug-in: PSP', ''])

webware/__init__.py

@@ -1,17 +1,19 @@
 """Webware for Python"""
 
-import sys
 
-
-def add_to_python_path():
+def addToSearchPath():
+    """Add the Webware package to the search path for Python modules."""
+    import sys
     webwarePath = __path__[0]
     if webwarePath not in sys.path:
         sys.path.insert(0, webwarePath)
 
 
-def load_plugins(path, settings=None, development=None):
+def mockAppWithPlugins(path=None, settings=None, development=None):
+    """Return a mock application with all plugins loaded."""
+    addToSearchPath()
     from MockApplication import MockApplication
     from PlugInLoader import PlugInLoader
     app = MockApplication(path, settings, development)
-    loader = PlugInLoader(app)
-    loader.loadPlugIns(app.setting('PlugIns'), verbose=False)
+    PlugInLoader(app).loadPlugIns()
+    return app