Add a functional vm_test for root_test.

This change renames the tools/images directory to tools/vm for clarity, and
adds a functional vm_test. Sharding is also added to the same test, and some
documentation added around key flags & variables to describe how they work.

Subsequent changes will add vm_tests for other cases, such as the runtime tests.

PiperOrigin-RevId: 307492245

1 files changed, 13 insertions, 1 deletions

diff --git a/test/root/BUILD b/test/root/BUILD
index ddc9b4955..05166673a 100644
--- a/test/root/BUILD
+++ b/test/root/BUILD
@@ -1,4 +1,5 @@
 load("//tools:defs.bzl", "go_library", "go_test")
+load("//tools/vm:defs.bzl", "vm_test")
 
 package(licenses = ["notice"])
 
@@ -24,7 +25,9 @@ go_test(
     library = ":root",
     tags = [
         # Requires docker and runsc to be configured before the test runs.
-        # Also test only runs as root.
+        # Also, the test needs to be run as root. Note that below, the
+        # root_vm_test relies on the default runtime 'runsc' being installed by
+        # the default installer.
         "manual",
         "local",
     ],
@@ -44,3 +47,12 @@ go_test(
         "@org_golang_x_sys//unix:go_default_library",
     ],
 )
+
+vm_test(
+    name = "root_vm_test",
+    shard_count = 1,
+    targets = [
+        "//tools/installers:shim",
+        ":root_test",
+    ],
+)