Mojo: Add a "pytest" to mojob.sh that runs Python unit tests.

mojo/tools/mojob.sh

Index: mojo/tools/mojob.sh
diff --git a/mojo/tools/mojob.sh b/mojo/tools/mojob.sh
index 7cf4066a93030761488b603caff543ea3f4ca5df..e4f9697a339f1ea6af9ca68c5892326e18ca551d 100755
--- a/mojo/tools/mojob.sh
+++ b/mojo/tools/mojob.sh
@@ -18,7 +18,8 @@ Usage: $(basename "$0") [command|option ...]
 command should be one of:
   build - Build.
   test - Run unit tests (does not build).
-  perftest - Run Release and Debug perf tests (does not build).
+  perftest - Run perf tests (does not build).
+  pytest - Run Python unit tests.
   gyp - Run gyp for mojo (does not sync), with clang.
   sync - Sync using gclient (does not run gyp).
   show-bash-alias - Outputs an appropriate bash alias for mojob. In bash do:
@@ -59,6 +60,12 @@ do_perftests() {
   "out/$1/mojo_public_system_perftests" || exit 1
 }
 
+do_pytests() {
+  echo "Running Python unit tests under mojo/public/tools/bindings/pylib ..."
+  python -m unittest \
+      discover -s mojo/public/tools/bindings/pylib -p "*_unittest.py"
+}
+
 do_gyp() {
   local gyp_defines="$(make_gyp_defines)"
   echo "Running gyp with GYP_DEFINES=$gyp_defines ..."
@@ -144,6 +151,9 @@ for arg in "$@"; do
       should_do_Debug && do_perftests Debug
       should_do_Release && do_perftests Release
       ;;
+    pytest)
+      do_pytests
+      ;;
     gyp)
       do_gyp
       ;;