add tasks for updating vendored libs

Author: RonnyPfannschmidt

tasks/__init__.py

@@ -4,6 +4,10 @@
 
 import invoke
 
-from . import generate
+from . import generate, vendoring
 
-ns = invoke.Collection(generate)
+
+ns = invoke.Collection(
+    generate,
+    vendoring
+)

tasks/vendoring.py

@@ -0,0 +1,21 @@
+from __future__ import absolute_import, print_function
+import py
+import invoke
+
+VENDOR_TARGET = py.path.local("_pytest/vendored_packages")
+GOOD_FILES = 'README.md', '__init__.py'
+
+@invoke.task()
+def remove_libs(ctx):
+    print("removing vendored libs")
+    for path in VENDOR_TARGET.listdir():
+        if path.basename not in GOOD_FILES:
+            print(" ", path)
+            path.remove()
+
+@invoke.task(pre=[remove_libs])
+def update_libs(ctx):
+    print("installing libs")
+    ctx.run("pip install -t {target} pluggy".format(target=VENDOR_TARGET))
+    ctx.run("git add {target}".format(target=VENDOR_TARGET))
+    print("please commit to finish the updae after running the tests")