[ggj][infra][2/5] feat: bazel rules support for integration test

rules_bazel/java/integration_test.bzl

@@ -0,0 +1,99 @@
+def _diff_integration_goldens_impl(ctx):
+    # Extract the Java source files from the generated 3 srcjars from API bazel target, 
+    # and put them in the temporary folder `codegen_tmp`.
+    # Compare the `codegen_tmp` with the goldens folder e.g `test/integration/goldens/redis`
+    # and save the differences in output file `diff_output.txt`.
+
+    diff_output = ctx.outputs.diff_output
+    check_diff_script = ctx.outputs.check_diff_script
+    gapic_library = ctx.attr.gapic_library
+    resource_name_library = ctx.attr.resource_name_library
+    test_library = ctx.attr.test_library
+    srcs = ctx.files.srcs
+    api_name = ctx.attr.name
+
+    script = """
+    mkdir codegen_tmp
+    unzip -j {input} -d codegen_tmp
+    unzip -j {input_resource_name} -d  codegen_tmp
+    unzip -j {input_test} -d codegen_tmp
+    cd codegen_tmp
+    # Remove unneeded non-Java files, like MANIFEST
+    rm -rf $(find . -type f ! -name "*.java")
+    cd ..
+    diff codegen_tmp test/integration/goldens/{api_name}/ > {diff_output}
+    # Bash `diff` command will return exit code 1 when there are differences between the two
+    # folders. So we explicitly `exit 0` after the diff command to avoid build failure.
+    exit 0
+    """.format(
+        diff_output = diff_output.path,
+        input = gapic_library[JavaInfo].source_jars[0].path,
+        input_resource_name = resource_name_library[JavaInfo].source_jars[0].path,
+        input_test = test_library[JavaInfo].source_jars[0].path,
+        api_name = api_name
+    )
+    ctx.actions.run_shell(
+        inputs = srcs + [
+            gapic_library[JavaInfo].source_jars[0], 
+            resource_name_library[JavaInfo].source_jars[0], 
+            test_library[JavaInfo].source_jars[0],
+        ],
+        outputs = [diff_output],
+        command = script,
+    )
+
+    # Check the generated diff_output file, if it is empty, that means there is no difference  
+    # between generated source code and goldens files, test should pass. If it is not empty, then 
+    # test will fail by exiting 1.
+
+    check_diff_script_content = """
+    # This will not print diff_output to the console unless `--test_output=all` option
+    # is enabled, it only emits the comparison results to the test.log.
+    # We could not copy the diff_output.txt to the test.log ($XML_OUTPUT_FILE) because that
+    # file is not existing at the moment. It is generated once test is finished.
+    cat $PWD/test/integration/{api_name}_diff_output.txt
+    if [ -s $PWD/test/integration/{api_name}_diff_output.txt ]
+    then
+        exit 1
+    fi
+    """.format(
+        api_name = api_name,
+    )
+
+    ctx.actions.write(
+        output = check_diff_script,
+        content = check_diff_script_content,
+    )
+    runfiles = ctx.runfiles(files = [ctx.outputs.diff_output])
+    return [DefaultInfo(executable = check_diff_script, runfiles = runfiles)]
+
+
+diff_integration_goldens_test = rule(
+    attrs = {
+        "gapic_library": attr.label(),
+        "resource_name_library": attr.label(),
+        "test_library": attr.label(),
+        "srcs": attr.label_list(
+            allow_files = True,
+            mandatory = True,
+        ), 
+    },
+    outputs = {
+        "diff_output": "%{name}_diff_output.txt",
+        "check_diff_script": "%{name}_check_diff_script.sh",
+    },
+    implementation = _diff_integration_goldens_impl,
+    test = True,
+)
+
+
+def integration_test(name, target, data):
+    # Bazel target `java_gapic_library` will generate 3 source jars including the
+    # the source Java code of the gapic_library, resource_name_library and test_library.
+    diff_integration_goldens_test(
+        name = name,
+        gapic_library = target,
+        resource_name_library = "%s_resource_name" % target,
+        test_library = "%s_test" % target,
+        srcs = data,
+    )

test/integration/BUILD.bazel

@@ -4,6 +4,11 @@ load(
     java_gapic_library = "java_gapic_library2",
 )
 
+load(
+    "//:rules_bazel/java/integration_test.bzl",
+    "integration_test",
+)
+
 package(default_visibility = ["//visibility:public"])
 
 ####################################################
@@ -50,3 +55,9 @@ java_gapic_library(
         "@com_google_googleapis//google/cloud/redis/v1:redis_java_proto",
     ],
 )
+
+integration_test(
+    name = "redis",
+    target = ":redis_java_gapic",
+    data = ["//test/integration/goldens/redis:goldens_files"],
+)