Open-source Bazel integration tests

It is a first batch of integration tests for Bazel. They tests some
basic behaviors and nominal cases of Bazel rules (especially they tests
the behavior of the examples provided in //examples).

--
MOS_MIGRATED_REVID=89440074
diff --git a/examples/java-native/BUILD b/examples/java-native/BUILD
new file mode 100644
index 0000000..b698a88
--- /dev/null
+++ b/examples/java-native/BUILD
@@ -0,0 +1,10 @@
+package(default_visibility = ["//visibility:public"])
+
+filegroup(
+    name = "srcs",
+    srcs = [
+        "//examples/java-native/src/main/java/com/example/myproject:srcs",
+        "//examples/java-native/src/main/resources:srcs",
+        "//examples/java-native/src/test/java/com/example/myproject:srcs",
+    ],
+)
diff --git a/examples/java-native/src/main/java/com/example/myproject/BUILD b/examples/java-native/src/main/java/com/example/myproject/BUILD
index 7176253..96087776 100644
--- a/examples/java-native/src/main/java/com/example/myproject/BUILD
+++ b/examples/java-native/src/main/java/com/example/myproject/BUILD
@@ -22,3 +22,8 @@
     srcs = ["Greeter.java"],
     resources = ["//examples/java-native/src/main/resources:greeting"],
 )
+
+filegroup(
+    name = "srcs",
+    srcs = ["BUILD"] + glob(["**/*.java"]),
+)
diff --git a/examples/java-native/src/main/resources/BUILD b/examples/java-native/src/main/resources/BUILD
index 8347a35..97aa937 100644
--- a/examples/java-native/src/main/resources/BUILD
+++ b/examples/java-native/src/main/resources/BUILD
@@ -4,3 +4,11 @@
     name = "greeting",
     srcs = ["greeting.txt"],
 )
+
+filegroup(
+    name = "srcs",
+    srcs = [
+        "BUILD",
+        "greeting.txt",
+    ],
+)
diff --git a/examples/java-native/src/test/java/com/example/myproject/BUILD b/examples/java-native/src/test/java/com/example/myproject/BUILD
index 8381076..9a91a82 100644
--- a/examples/java-native/src/test/java/com/example/myproject/BUILD
+++ b/examples/java-native/src/test/java/com/example/myproject/BUILD
@@ -31,3 +31,9 @@
         "//third_party:junit4",
     ],
 )
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**/*.java"]) + ["BUILD"],
+    visibility = ["//examples/java-native:__pkg__"],
+)