Adding test to create BACKEND_BUSY error

Creates multiple child procs and creates opearations in it and
parent proc waits for all child procs operations status, expects
one or more opearations to fail with backeend busy error.

Bug: 194359114
Test: atest keystore2_client_test
Change-Id: I52f95a7cfd031d80c88bfc2ca478a26572f40150
diff --git a/keystore2/tests/Android.bp b/keystore2/tests/Android.bp
new file mode 100644
index 0000000..21784a1
--- /dev/null
+++ b/keystore2/tests/Android.bp
@@ -0,0 +1,39 @@
+// Copyright 2022, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+rust_test {
+    name: "keystore2_client_tests",
+    defaults: [
+        "keymint_use_latest_hal_aidl_rust",
+        "keystore2_use_latest_aidl_rust",
+    ],
+    srcs: ["keystore2_client_tests.rs"],
+    test_suites: [
+        "general-tests",
+    ],
+    test_config: "AndroidTest.xml",
+
+    rustlibs: [
+        "librustutils",
+        "libkeystore2_test_utils",
+        "libnix",
+        "libanyhow",
+        "libbinder_rs",
+        "liblazy_static",
+        "liblibc",
+        "libserde",
+        "libthiserror",
+    ],
+    require_root: true,
+}