GafferTractorTest : Test using mock API if Tractor unavailable

This allows us to run GafferTractorTest and GafferTractorUITest in CI even though we don't have Tractor installed.

.github/workflows/main.yml

@@ -64,7 +64,7 @@ jobs:
             publish: true
             containerImage:
             testRunner: Invoke-Expression
-            testArguments: -excludedCategories performance GafferTest GafferVDBTest GafferUSDTest GafferSceneTest GafferDispatchTest GafferOSLTest GafferImageTest GafferUITest GafferImageUITest GafferSceneUITest GafferDispatchUITest GafferOSLUITest GafferUSDUITest GafferVDBUITest GafferDelightUITest
+            testArguments: -excludedCategories performance GafferTest GafferVDBTest GafferUSDTest GafferSceneTest GafferDispatchTest GafferOSLTest GafferImageTest GafferUITest GafferImageUITest GafferSceneUITest GafferDispatchUITest GafferOSLUITest GafferUSDUITest GafferVDBUITest GafferDelightUITest GafferTractorTest GafferTractorUITest
             sconsCacheMegabytes: 400
 
     runs-on: ${{ matrix.os }}

Changes.md

@@ -9,6 +9,12 @@ Improvements
 - TaskList, FrameMask : Reimplemented in C++ for improved performance.
 - Cache : Increased default computation cache size to 8Gb. Call `Gaffer.ValuePlug.setCacheMemoryLimit()` from a startup file to override this.
 
+API
+---
+
+- GafferTractor : Added `tractorAPI()` method used for accessing the `tractor.api.author` module.
+- GafferTractorTest : Added `tractorAPI()` method which returns a mock API if Tractor is not available. This allows the GafferTractor module to be tested without Tractor being installed.
+
 Breaking Changes
 ----------------
 

python/GafferTractor/TractorDispatcher.py

@@ -36,19 +36,20 @@
 
 import os
 
-import tractor.api.author as author
-
 import IECore
 
 import Gaffer
 import GafferDispatch
+import GafferTractor
 
 class TractorDispatcher( GafferDispatch.Dispatcher ) :
 
 	def __init__( self, name = "TractorDispatcher" ) :
 
 		GafferDispatch.Dispatcher.__init__( self, name )
 
+		self.__tractorAPI = GafferTractor.tractorAPI()
+
 		self["service"] = Gaffer.StringPlug( defaultValue = '"*"' )
 		self["envKey"] = Gaffer.StringPlug()
 
@@ -82,7 +83,7 @@ def _doDispatch( self, rootBatch ) :
 
 		context = Gaffer.Context.current()
 
-		job = author.Job(
+		job = self.__tractorAPI.Job(
 			## \todo Remove these manual substitutions once #887 is resolved.
 			title = context.substitute( self["jobName"].getValue() ) or "untitled",
 			service = context.substitute( self["service"].getValue() ),
@@ -143,7 +144,7 @@ def __acquireTask( self, batch, dispatchData ) :
 		# Make a task.
 
 		nodeName = batch.node().relativeName( dispatchData["scriptNode"] )
-		task = author.Task( title = nodeName )
+		task = self.__tractorAPI.Task( title = nodeName )
 
 		if batch.frames() :
 
@@ -172,7 +173,7 @@ def __acquireTask( self, batch, dispatchData ) :
 			# Create a Tractor command to execute that command line, and add
 			# it to the task.
 
-			command = author.Command( argv = args )
+			command = self.__tractorAPI.Command( argv = args )
 			task.addCommand( command )
 
 			# Apply any custom dispatch settings to the command.

python/GafferTractor/__init__.py

@@ -36,4 +36,12 @@
 
 from .TractorDispatcher import TractorDispatcher
 
+## Returns the `tractor.api.author` module, and must be the _only_
+# method used to access that module in GafferTractor. This allows us
+# to insert a mock API for testing in GafferTractorTest.
+def tractorAPI() :
+
+	from tractor.api.author import author
+	return author
+
 __import__( "IECore" ).loadConfig( "GAFFER_STARTUP_PATHS", subdirectory = "GafferTractor" )

python/GafferTractorTest/ModuleTest.py

@@ -41,7 +41,6 @@
 
 import GafferTest
 
-@unittest.skipIf( not IECore.SearchPath( sys.path ).find( "tractor" ), "Tractor not available" )
 class ModuleTest( GafferTest.TestCase ) :
 
 	def testDoesNotImportUI( self ) :

python/GafferTractorTest/TractorDispatcherTest.py

@@ -35,8 +35,10 @@
 ##########################################################################
 
 import unittest
+import unittest.mock
 import inspect
 import sys
+
 import imath
 
 import IECore
@@ -45,23 +47,21 @@
 import GafferTest
 import GafferDispatch
 import GafferDispatchTest
+import GafferTractor
+import GafferTractorTest
 
-@unittest.skipIf( not IECore.SearchPath( sys.path ).find( "tractor" ), "Tractor not available" )
+@unittest.mock.patch( "GafferTractor.tractorAPI", new = GafferTractorTest.tractorAPI )
 class TractorDispatcherTest( GafferTest.TestCase ) :
 
 	def __dispatcher( self ) :
 
-		import GafferTractor
-
 		dispatcher = GafferTractor.TractorDispatcher()
 		dispatcher["jobsDirectory"].setValue( self.temporaryDirectory() / "testJobDirectory" )
 
 		return dispatcher
 
 	def __job( self, nodes, dispatcher = None ) :
 
-		import GafferTractor
-
 		jobs = []
 		def f( dispatcher, job ) :
 
@@ -78,8 +78,6 @@ def f( dispatcher, job ) :
 
 	def testPreSpoolSignal( self ) :
 
-		import GafferTractor
-
 		s = Gaffer.ScriptNode()
 		s["n"] = GafferDispatchTest.LoggingTaskNode()
 
@@ -187,8 +185,6 @@ def testPreTasks( self ) :
 
 	def testSharedPreTasks( self ) :
 
-		import tractor.api.author as author
-
 		#   n1
 		#  / \
 		# i1 i2
@@ -221,7 +217,10 @@ def testSharedPreTasks( self ) :
 		self.assertEqual( job.subtasks[0].subtasks[0].subtasks[0].title, "n1 1" )
 		self.assertEqual( job.subtasks[0].subtasks[1].subtasks[0].title, "n1 1" )
 
-		self.assertTrue( isinstance( job.subtasks[0].subtasks[1].subtasks[0], author.Instance ) )
+		self.assertIsInstance(
+			job.subtasks[0].subtasks[1].subtasks[0],
+			GafferTractor.tractorAPI().Instance
+		)
 
 	def testTaskPlugs( self ) :
 
@@ -241,14 +240,10 @@ def testTaskPlugs( self ) :
 
 	def testTypeNamePrefixes( self ) :
 
-		import GafferTractor
-
 		self.assertTypeNamesArePrefixed( GafferTractor )
 
 	def testDefaultNames( self ) :
 
-		import GafferTractor
-
 		self.assertDefaultNamesAreCorrect( GafferTractor )
 
 	def testTasksWithoutCommands( self ) :

python/GafferTractorTest/__init__.py

@@ -34,6 +34,98 @@
 #
 ##########################################################################
 
+__mockAPI = None
+
+# Testing replacement for `GafferTractor.tractorAPI()`. This returns
+# the same `tractor.api.author` module if it is available, but otherwise
+# returns a mock module sufficient for running the unit tests without
+# Tractor present.
+def tractorAPI() :
+
+	import types
+	import contextlib
+
+	# Use the real API if it is available.
+
+	with contextlib.suppress( ImportError ) :
+		from tractor.api.author import author
+		return author
+
+	# Otherwise build mock version. The goal here is not to emulate the whole
+	# Tractor API, but to provide the bare minimum needed to run the unit tests.
+
+	global __mockAPI
+	if __mockAPI is not None :
+		return __mockAPI
+
+	class TaskBased :
+
+		def __init__( self, **kw ) :
+
+			for key, value in kw.items() :
+				setattr( self, key, value )
+
+			self.subtasks = []
+
+		def addChild( self, task ) :
+
+			if task.parent is None :
+				self.subtasks.append( task )
+				task.parent = self
+			else :
+				self.subtasks.append( Instance( title = task.title ) )
+
+	class Job( TaskBased ) :
+
+		__slots__ = [ "title", "service", "envkey" ]
+
+		def asTcl( self ) :
+
+			return "# Mock serialisation"
+
+		def spool( self, block = False ) :
+
+			pass
+
+	class Task( TaskBased ) :
+
+		__slots__ = [ "title", "service", "envkey", "parent" ]
+
+		def __init__( self, **kw ) :
+
+			TaskBased.__init__( self, **kw )
+			self.cmds = []
+			self.parent = None
+
+		def addCommand( self, command ) :
+
+			self.cmds.append( command )
+
+	class Instance :
+
+		__slots__ = [ "title" ]
+
+		def __init__( self, title ) :
+
+			self.title = title
+
+	class Command :
+
+		__slots__ = [ "argv", "service", "tags" ]
+
+		def __init__( self, **kw ) :
+
+			for key, value in kw.items() :
+				setattr( self, key, value )
+
+	__mockAPI = types.ModuleType( "author" )
+	__mockAPI.Job = Job
+	__mockAPI.Task = Task
+	__mockAPI.Instance = Instance
+	__mockAPI.Command = Command
+
+	return __mockAPI
+
 from .TractorDispatcherTest import TractorDispatcherTest
 from .ModuleTest import ModuleTest
 

python/GafferTractorUITest/DocumentationTest.py

@@ -41,15 +41,14 @@
 
 import GafferUITest
 import GafferDispatch
+import GafferDispatchUI
+import GafferTractor
+import GafferTractorUI
 
-@unittest.skipIf( not IECore.SearchPath( sys.path ).find( "tractor" ), "Tractor not available" )
 class DocumentationTest( GafferUITest.TestCase ) :
 
 	def test( self ) :
 
-		import GafferTractor
-		import GafferTractorUI
-
 		self.maxDiff = None
 		self.assertNodesAreDocumented( GafferTractor )
 		# Also test GafferDispatch because we add plugs to

startup/gui/menus.py

@@ -570,8 +570,11 @@ def __usdLightCreator( lightType ) :
 
 with contextlib.suppress( ImportError ) :
 
-	import GafferTractorUI
+	# Raises if Tractor not available, thus avoiding registering the
+	# TractorDispatcher.
+	import tractor.api.author
 
+	import GafferTractorUI
 
 ## Metadata cleanup
 ###########################################################################

startup/gui/project.py

@@ -110,6 +110,7 @@ def __projectBookmark( widget, location ) :
 
 dispatchers = [ GafferDispatch.LocalDispatcher ]
 with contextlib.suppress( ImportError ) :
+	import tractor.api.author # Raises if Tractor not available
 	import GafferTractor
 	dispatchers.append( GafferTractor.TractorDispatcher )