Add an example that shows how to use the cpu:<num> tag for tests.

Also serves as an example for bug bazelbuild#3106.

PiperOrigin-RevId: 158116940

examples/java-native/src/test/java/com/example/myproject/BUILD

@@ -35,6 +35,40 @@ java_test(
     deps = ["//third_party:junit4"],
 )
 
+# This exercises the "cpu:<num>" tag.
+#
+# Expected behavior:
+# test0 and test1 run together then one of the other two alone, and then the remaining one alone.
+java_test(
+    name = "sleep0",
+    srcs = ["TestSleep.java"],
+    test_class = "com.example.myproject.TestSleep",
+    deps = ["//third_party:junit4"],
+)
+
+java_test(
+    name = "sleep1",
+    srcs = ["TestSleep.java"],
+    test_class = "com.example.myproject.TestSleep",
+    deps = ["//third_party:junit4"],
+)
+
+java_test(
+    name = "sleep2",
+    srcs = ["TestSleep.java"],
+    tags = ["cpu:20000"],
+    test_class = "com.example.myproject.TestSleep",
+    deps = ["//third_party:junit4"],
+)
+
+java_test(
+    name = "sleep3",
+    srcs = ["TestSleep.java"],
+    tags = ["cpu:20000"],
+    test_class = "com.example.myproject.TestSleep",
+    deps = ["//third_party:junit4"],
+)
+
 # This attempts to run TestCustomGreeting.java without any resources, so fails.
 java_test(
     name = "resource-fail",

examples/java-native/src/test/java/com/example/myproject/TestSleep.java

@@ -0,0 +1,12 @@
+package com.example.myproject;
+
+import org.junit.Test;
+
+/** Contains a single test that just sleeps for 15 seconds and then succeeds. */
+public class TestSleep {
+  @Test
+  public void testSleep() throws Exception {
+    // Sleep for 15 seconds.
+    Thread.sleep(15 * 1000);
+  }
+}