[bazel] Add macros to build jni code and java tests (#7693)

wpiunits/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@rules_java//java:defs.bzl", "java_binary", "java_library")
+load("//shared/bazel/rules:java_rules.bzl", "wpilib_java_junit5_test")
 
 java_library(
     name = "wpiunits",
@@ -7,6 +8,14 @@ java_library(
     deps = [],
 )
 
+wpilib_java_junit5_test(
+    name = "wpiunits-test",
+    srcs = glob(["src/test/java/**/*.java"]),
+    deps = [
+        ":wpiunits",
+    ],
+)
+
 java_binary(
     name = "DevMain-Java",
     srcs = ["src/dev/java/edu/wpi/first/units/DevMain.java"],