chore: make integration test infrastructure sane (#904)

The you-can-do-anything-in-bazel mentality can easily lure one to a state where you are programming a build with a build tool instead of configuring a build.

I just extracted the shell script portion out of a `.bzl` file into a file.

This should also help switching to any build system from Bazel.

.gitignore

@@ -1,5 +1,6 @@
 # Bazel.
 bazel-*
+.gradle/
 
 # IDE
 .idea

rules_bazel/java/integration_test.bzl

@@ -1,103 +1,3 @@
-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 {input} -d codegen_tmp
-    unzip {input_resource_name} -d  codegen_tmp
-    unzip {input_test} -d codegen_tmp
-    cd codegen_tmp
-    # Remove unneeded non-Java files, like MANIFEST
-    rm -rf $(find ./ -type f ! -name '*.java' -a ! -name '*gapic_metadata.json')
-    rm -rf $(find ./ -type f -name 'PlaceholderFile.java')
-    rm -r $(find ./ -type d -empty)
-    cd ..
-    diff -r codegen_tmp test/integration/goldens/{api_name} > {diff_output}
-    # Bash `diff` command will return exit code 1 when there are differences between the two
-    # folders. So we explicitly `exit 0` after the diff command to avoid build failure.
-    exit 0
-    """.format(
-        diff_output = diff_output.path,
-        input = gapic_library[JavaInfo].source_jars[0].path,
-        input_resource_name = resource_name_library[JavaInfo].source_jars[0].path,
-        input_test = test_library[JavaInfo].source_jars[0].path,
-        api_name = api_name,
-    )
-    ctx.actions.run_shell(
-        inputs = srcs + [
-            gapic_library[JavaInfo].source_jars[0],
-            resource_name_library[JavaInfo].source_jars[0],
-            test_library[JavaInfo].source_jars[0],
-        ],
-        outputs = [diff_output],
-        command = script,
-    )
-
-    # Check the generated diff_output file, if it is empty, that means there is no difference
-    # between generated source code and goldens files, test should pass. If it is not empty, then
-    # test will fail by exiting 1.
-
-    check_diff_script_content = """
-    # This will not print diff_output to the console unless `--test_output=all` option
-    # is enabled, it only emits the comparison results to the test.log.
-    # We could not copy the diff_output.txt to the test.log ($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,
-    )
-
 def _overwrite_golden_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`, zip as `goldens_output_zip`.

scripts/BUILD.bazel

@@ -0,0 +1,3 @@
+package(default_visibility = ["//test/integration:__pkg__"])
+
+exports_files(["diff_gen_and_golden.sh"])

scripts/diff_gen_and_golden.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -o errexit
+
+API_NAME=$1
+RAW_SRCJAR=$( find . -name '*_java_gapic_srcjar_raw.srcjar' )
+
+mkdir unpacked src
+cd unpacked
+unzip -q -c "../${RAW_SRCJAR}" temp-codegen.srcjar | jar x
+cp -rf src/main/java/* ../src
+cp -rf src/test/java/* ../src
+[ -d proto ] && cp -rf proto/src/main/java/* ../src
+cd ..
+
+# Remove unneeded non-Java files, like MANIFEST
+find src -type f ! -name '*.java' -a ! -name '*gapic_metadata.json' -delete
+find src -type f -name 'PlaceholderFile.java' -delete
+find src -type d -empty -delete
+
+# This will not print diff_output to the console unless `--test_output=all` option
+# is enabled, it only emits the comparison results to the test.log.
+diff -ru src test/integration/goldens/${API_NAME}

test/integration/BUILD.bazel

@@ -9,11 +9,7 @@ load(
     "java_gapic_assembly_gradle_pkg",
 )
 load("@rules_gapic//:gapic.bzl", "proto_library_with_info")
-load(
-    "//:rules_bazel/java/integration_test.bzl",
-    "golden_update",
-    "integration_test",
-)
+load("//:rules_bazel/java/integration_test.bzl", "golden_update")
 load("@rules_proto//proto:defs.bzl", "proto_library")
 
 package(default_visibility = ["//visibility:public"])
@@ -49,10 +45,14 @@ API_GAPIC_TARGETS = {
     "compute": "@com_google_googleapis_discovery//google/cloud/compute/v1:compute_small_java_gapic",
 }
 
-[integration_test(
+[sh_test(
     name = lib_name,
-    data = ["//test/integration/goldens/%s:goldens_files" % lib_name],
-    target = API_GAPIC_TARGETS[lib_name],
+    srcs = ["//scripts:diff_gen_and_golden.sh"],
+    args = [lib_name],
+    data = [
+      API_GAPIC_TARGETS[lib_name] + "_srcjar_raw.srcjar",
+      "//test/integration/goldens/%s:goldens_files" % lib_name,
+    ],
 ) for lib_name in INTEGRATION_TEST_LIBRARIES]
 
 [golden_update(