Address typing issues hidden by memoization.caching (#322)

.github/workflows/ci.yml

@@ -212,6 +212,9 @@ jobs:
 
         # set a minimum confidence to ignore known false positives
         vulture --min-confidence 61 __app__ 
+
+        ../ci/disable-py-cache.sh
+        mypy __app__ ./tests
   afl:
     runs-on: ubuntu-18.04
     steps:

src/api-service/__app__/onefuzzlib/azure/vm.py

@@ -41,7 +41,7 @@ def get_vm(name: str) -> Optional[VirtualMachine]:
 
 def create_vm(
     name: str,
-    location: str,
+    location: Region,
     vm_sku: str,
     image: str,
     password: str,

src/api-service/__app__/onefuzzlib/tasks/main.py

@@ -47,6 +47,8 @@ class Task(BASE_TASK, ORMMixin):
     ) -> Union["Task", Error]:
         if config.vm:
             os = get_os(config.vm.region, config.vm.image)
+            if isinstance(os, Error):
+                return os
         elif config.pool:
             pool = Pool.get_by_name(config.pool.pool_name)
             if isinstance(pool, Error):

src/ci/disable-py-cache.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# Temporary work-around to improve the efficacy of static analysis of functions
+# decorated with memoization.cached.
+#
+# For more information:
+# https://github.com/lonelyenvoy/python-memoization/issues/16
+
+set -ex
+
+SCRIPT_DIR=$(dirname ${BASH_SOURCE[0]})
+
+sed -i "s/^from memoization import cached/##### from memoization import cached/" $(find . -name '*.py' -not -path .python_packages)
+sed -i "s/^@cached/##### @cached/" $(find . -name '*.py' -not -path .python_packages)

src/ci/enable-py-cache.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+# Temporary work-around to improve the efficacy of static analysis of functions
+# decorated with memoization.cached.
+#
+# For more information:
+# https://github.com/lonelyenvoy/python-memoization/issues/16
+
+set -ex
+
+SCRIPT_DIR=$(dirname ${BASH_SOURCE[0]})
+
+sed -i "s/^##### from memoization import cached/from memoization import cached/" $(find . -name '*.py' -not -path .python_packages)
+sed -i "s/^##### @cached/@cached/" $(find . -name '*.py' -not -path .python_packages)