Add rust_test and update TEST_MAPPING

Test: atest -c --include-subdirs external/rust/crates
Change-Id: Ica179004c4c689a8c619824db4bbe24d1fff285f
diff --git a/Android.bp b/Android.bp
index 441c7ff..a1e6550 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,4 @@
-// This file is generated by cargo2android.py --run --dependencies --device.
+// This file is generated by cargo2android.py --run --dependencies --device --tests.
 
 rust_library {
     name: "libunicode_width",
@@ -11,3 +11,28 @@
         "default",
     ],
 }
+
+rust_defaults {
+    name: "unicode-width_defaults",
+    crate_name: "unicode_width",
+    test_suites: ["general-tests"],
+    auto_gen_config: true,
+    edition: "2015",
+    features: [
+        "default",
+    ],
+}
+
+rust_test_host {
+    name: "unicode-width_host_test_src_lib",
+    defaults: ["unicode-width_defaults"],
+    // has rustc warnings
+    srcs: ["src/lib.rs"],
+}
+
+rust_test {
+    name: "unicode-width_device_test_src_lib",
+    defaults: ["unicode-width_defaults"],
+    // has rustc warnings
+    srcs: ["src/lib.rs"],
+}