# Buggy code
def install_product(
    app, product_dir, product_name, meta_types, folder_permissions, raise_exc=None
):
    if not _is_package(product_dir, product_name):
        return

    __traceback_info__ = product_name
    global_dict = globals()
    product = __import__(
        "Products.%s" % product_name, global_dict, global_dict, ("__doc__",)
    )

    # Install items into the misc_ namespace, used by products
    # and the framework itself to store common static resources
    # like icon images.
    misc_ = pgetattr(product, "misc_", {})
    if misc_:
        if isinstance(misc_, dict):
            misc_ = Misc_(product_name, misc_)
        Application.misc_.__dict__[product_name] = misc_

    productObject = FactoryDispatcher.Product(product_name)
    context = ProductContext(productObject, None, product)

    # Look for an 'initialize' method in the product.
    initmethod = pgetattr(product, "initialize", None)
    if initmethod is not None:
        initmethod(context)


# Traceback (TypeError)
Running plone.app.testing.layers.PloneFixture tests:
Tear down Testing.ZopeTestCase.layer.ZopeLite in 0.000 seconds.
Set up plone.testing.zca.LayerCleanup in 0.000 seconds.
Set up plone.testing.z2.Startup in 0.058 seconds.
Set up plone.app.testing.layers.PloneFixture Traceback (most recent call last):
File "/home/jenkins/.buildout/eggs/zope.testrunner-4.7.0-py2.7.egg/zope/testrunner/runner.py", line 400, in run_layer
setup_layer(options, layer, setup_layers)
File "/home/jenkins/.buildout/eggs/zope.testrunner-4.7.0-py2.7.egg/zope/testrunner/runner.py", line 713, in setup_layer
layer.setUp()
File "/home/jenkins/workspace/plip-zope4/src/plone.app.testing/plone/app/testing/layers.py", line 107, in setUp
self.setUpProducts(app)
File "/home/jenkins/workspace/plip-zope4/src/plone.app.testing/plone/app/testing/layers.py", line 186, in setUpProducts
z2.installProduct(app, p)
File "/home/jenkins/workspace/plip-zope4/src/plone.testing/src/plone/testing/z2.py", line 68, in installProduct
raise_exc=1)
File "/home/jenkins/workspace/plip-zope4/src/Zope/src/OFS/Application.py", line 396, in install_product
Application.misc_.__dict__[product_name] = misc_
- __traceback_info__: ExternalEditor
TypeError: 'dictproxy' object does not support item assignment

# Fixed code
def install_product(
    app, product_dir, product_name, meta_types, folder_permissions, raise_exc=None
):
    if not _is_package(product_dir, product_name):
        return

    __traceback_info__ = product_name
    global_dict = globals()
    product = __import__(
        "Products.%s" % product_name, global_dict, global_dict, ("__doc__",)
    )

    # Install items into the misc_ namespace, used by products
    # and the framework itself to store common static resources
    # like icon images.
    misc_ = pgetattr(product, "misc_", {})
    if misc_:
        if isinstance(misc_, dict):
            misc_ = Misc_(product_name, misc_)
        setattr(Application.misc_, product_name, misc_)

    productObject = FactoryDispatcher.Product(product_name)
    context = ProductContext(productObject, None, product)

    # Look for an 'initialize' method in the product.
    initmethod = pgetattr(product, "initialize", None)
    if initmethod is not None:
        initmethod(context)