Layers: Unittesting - make them granular

Some tests may break Blender, which makes the entire unittest routine to fail.
They are now I isolate the tests into individual files

Kudos to Sybren Stüvel and Sergey Sharybin for the advice.

Note: at the moment test_link.py is failing (since a41bbfb7)

tests/python/render_layer/render_layer_common.py

@@ -0,0 +1,245 @@
+import unittest
+
+# ############################################################
+# Layer Collection Crawler
+# ############################################################
+
+def listbase_iter(data, struct, listbase):
+    element = data.get_pointer((struct, listbase, b'first'))
+    while element is not None:
+        yield element
+        element = element.get_pointer(b'next')
+
+
+def linkdata_iter(collection, data):
+    element = collection.get_pointer((data, b'first'))
+    while element is not None:
+        yield element
+        element = element.get_pointer(b'next')
+
+
+def get_layer_collection(layer_collection):
+    data = {}
+    flag = layer_collection.get(b'flag')
+
+    data['is_visible']    = (flag & (1 << 0)) != 0;
+    data['is_selectable'] = (flag & (1 << 1)) != 0;
+    data['is_folded']     = (flag & (1 << 2)) != 0;
+
+    scene_collection = layer_collection.get_pointer(b'scene_collection')
+    if scene_collection is None:
+        name = 'Fail!'
+    else:
+        name = scene_collection.get(b'name')
+    data['name'] = name
+
+    objects = []
+    for link in linkdata_iter(layer_collection, b'object_bases'):
+        ob_base = link.get_pointer(b'data')
+        ob = ob_base.get_pointer(b'object')
+        objects.append(ob.get((b'id', b'name'))[2:])
+    data['objects'] = objects
+
+    collections = {}
+    for nested_layer_collection in linkdata_iter(layer_collection, b'layer_collections'):
+        subname, subdata = get_layer_collection(nested_layer_collection)
+        collections[subname] = subdata
+    data['collections'] = collections
+
+    return name, data
+
+
+def get_layer(layer):
+    data = {}
+    name = layer.get(b'name')
+
+    data['name'] = name
+    data['active_object'] = layer.get((b'basact', b'object', b'id', b'name'))[2:]
+    data['engine'] = layer.get(b'engine')
+
+    objects = []
+    for link in linkdata_iter(layer, b'object_bases'):
+        ob = link.get_pointer(b'object')
+        objects.append(ob.get((b'id', b'name'))[2:])
+    data['objects'] = objects
+
+    collections = {}
+    for layer_collection in linkdata_iter(layer, b'layer_collections'):
+        subname, subdata = get_layer_collection(layer_collection)
+        collections[subname] = subdata
+    data['collections'] = collections
+
+    return name, data
+
+
+def get_layers(scene):
+    """Return all the render layers and their data"""
+    layers = {}
+    for layer in linkdata_iter(scene, b'render_layers'):
+        name, data = get_layer(layer)
+        layers[name] = data
+    return layers
+
+
+def get_scene_collection_objects(collection, listbase):
+    objects = []
+    for link in linkdata_iter(collection, listbase):
+        ob = link.get_pointer(b'data')
+        if ob is None:
+            name  = 'Fail!'
+        else:
+            name = ob.get((b'id', b'name'))[2:]
+        objects.append(name)
+    return objects
+
+
+def get_scene_collection(collection):
+    """"""
+    data = {}
+    name = collection.get(b'name')
+
+    data['name'] = name
+    data['filter'] = collection.get(b'filter')
+
+    data['objects'] = get_scene_collection_objects(collection, b'objects')
+    data['filter_objects'] = get_scene_collection_objects(collection, b'filter_objects')
+
+    collections = {}
+    for nested_collection in linkdata_iter(collection, b'scene_collections'):
+        subname, subdata = get_scene_collection(nested_collection)
+        collections[subname] = subdata
+    data['collections'] = collections
+
+    return name, data
+
+
+def get_scene_collections(scene):
+    """Return all the scene collections ahd their data"""
+    master_collection = scene.get_pointer(b'collection')
+    return get_scene_collection(master_collection)
+
+
+def query_scene(filepath, name, callbacks):
+    """Return the equivalent to bpy.context.scene"""
+    import blendfile
+    with blendfile.open_blend(filepath) as blend:
+        scenes = [block for block in blend.blocks if block.code == b'SC']
+        for scene in scenes:
+            if scene.get((b'id', b'name'))[2:] == name:
+                output = []
+                for callback in callbacks:
+                    output.append(callback(scene))
+                return output
+
+
+# ############################################################
+# Utils
+# ############################################################
+
+def import_blendfile():
+    import bpy
+    import os, sys
+    path = os.path.join(
+            bpy.utils.resource_path('LOCAL'),
+            'scripts',
+            'addons',
+            'io_blend_utils',
+            'blend',
+            )
+
+    if path not in sys.path:
+        sys.path.append(path)
+
+
+def dump(data):
+    import json
+    return json.dumps(
+            data,
+            sort_keys=True,
+            indent=4,
+            separators=(',', ': '),
+            )
+
+
+# ############################################################
+# Tests
+# ############################################################
+
+PDB = False
+DUMP_DIFF = True
+
+def compare_files(file_a, file_b):
+    import filecmp
+
+    if not filecmp.cmp(
+        file_a,
+        file_b):
+
+        if DUMP_DIFF:
+            import subprocess
+            subprocess.call(["diff", "-u", file_a, file_b])
+
+        if PDB:
+            import pdb
+            print("Files differ:", file_a, file_b)
+            pdb.set_trace()
+
+        return False
+
+    return True
+
+
+class RenderLayerTesting(unittest.TestCase):
+    _test_simple = False
+    _extra_arguments = []
+
+    @classmethod
+    def setUpClass(cls):
+        """Runs once"""
+        cls.pretest_import_blendfile()
+        cls.pretest_parsing()
+
+    @classmethod
+    def setUp(cls):
+        """Runs once per test"""
+        import bpy
+        bpy.ops.wm.read_factory_settings()
+
+    def path_exists(self, filepath):
+        import os
+        self.assertTrue(
+                os.path.exists(filepath),
+                "Test file \"{0}\" not found".format(filepath))
+
+    @classmethod
+    def get_root(cls):
+        """
+        return the folder with the test files
+        """
+        arguments = {}
+        for argument in cls._extra_arguments:
+            name, value = argument.split('=')
+            cls.assertTrue(name and name.startswith("--"), "Invalid argument \"{0}\"".format(argument))
+            cls.assertTrue(value, "Invalid argument \"{0}\"".format(argument))
+            arguments[name[2:]] = value.strip('"')
+
+        return arguments.get('testdir')
+
+    @classmethod
+    def pretest_parsing(cls):
+        """
+        Test if the arguments are properly set, and store ROOT
+        name has extra _ because we need this test to run first
+        """
+        root = cls.get_root()
+        cls.assertTrue(root, "Testdir not set")
+
+    @staticmethod
+    def pretest_import_blendfile():
+        """
+        Make sure blendfile imports with no problems
+        name has extra _ because we need this test to run first
+        """
+        import_blendfile()
+        import blendfile
+