test-wrapper: add empty impl + Bazel flag

This commit adds:

- the skeleton implementation of the Windows
  native test wrapper

- a depenency on the native test wrapper from test
  rules, through the new $test_wrapper rule
  attribute

- the --windows_native_test_wrapper Bazel flag,
  which is currently a no-op

See bazelbuild#5508

Change-Id: I8df95c8ce8bab53c51c257698ec95416065a836e

src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java

@@ -165,6 +165,11 @@ public Object getDefault(AttributeMap rule) {
                   .nonconfigurable("policy decision: should be consistent across configurations"))
           .add(attr("args", STRING_LIST))
           // Input files for every test action
+          .add(
+              attr("$test_wrapper", LABEL)
+                  .cfg(HostTransition.INSTANCE)
+                  .singleArtifact()
+                  .value(env.getToolsLabel("//tools/test:test_wrapper")))
           .add(
               attr("$test_runtime", LABEL_LIST)
                   .cfg(HostTransition.INSTANCE)

src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java

@@ -165,6 +165,12 @@ public static final RuleClass getTestBaseRule(String toolsRepository) {
                     "policy decision: this should be consistent across configurations"))
         .add(attr("args", STRING_LIST))
         // Input files for every test action
+        .add(
+            attr("$test_wrapper", LABEL)
+                .cfg(HostTransition.INSTANCE)
+                .singleArtifact()
+                .value(
+                    labelCache.getUnchecked(toolsRepository + "//tools/test:test_wrapper")))
         .add(
             attr("$test_runtime", LABEL_LIST)
                 .cfg(HostTransition.INSTANCE)

src/main/java/com/google/devtools/build/lib/analysis/test/TestConfiguration.java

@@ -216,6 +216,24 @@ public static class TestOptions extends FragmentOptions {
     )
     public Label coverageReportGenerator;
 
+    @Option(
+      name = "windows_native_test_wrapper",
+      // Undocumented: this features is under development and not yet ready for production use.
+      // We define the flag only in order to be able to test the feature.
+      // Design:
+      // https://github.com/laszlocsomor/proposals/blob/win-test-runner/designs/2018-07-18-windows-native-test-runner.md
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      // Affects loading and analysis: this flag affects which target Bazel loads and creates test
+      // actions with on Windows.
+      effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
+      defaultValue = "false",
+      help =
+          "Do not use yet, this flag's functionality is not yet implemented. "
+              + "(On Windows: if true, uses the C++ test wrapper to run tests, otherwise uses "
+              + "tools/test/test-setup.sh as on other platforms. On other platforms: no-op.)"
+    )
+    public boolean windowsNativeTestWrapper;
+
     @Override
     public Map<String, Set<Label>> getDefaultsLabels() {
       return ImmutableMap.<String, Set<Label>>of(
@@ -298,6 +316,10 @@ public Label getCoverageReportGenerator(){
     return options.coverageReportGenerator;
   }
 
+  public boolean isUsingWindowsNativeTestWrapper() {
+    return options.windowsNativeTestWrapper;
+  }
+
   /**
    * @return number of times the given test should run. If the test doesn't match any of the
    *     filters, runs it once.

tools/test/BUILD

@@ -33,6 +33,17 @@ filegroup(
     srcs = ["@bazel_tools//tools/test/LcovMerger/java/com/google/devtools/lcovmerger:Main"],
 )
 
+cc_binary(
+    name = "test_wrapper",
+    srcs = select({
+        "@bazel_tools//src/conditions:windows": ["windows/test_wrapper.cc"],
+        # Dummy source file, so this rule can be built on non-Windows platforms
+        # (when building all targets in this package).
+        "//conditions:default": ["windows/dummy.cc"],
+    }),
+    visibility = ["//visibility:private"],
+)
+
 filegroup(
     name = "srcs",
     srcs = glob(["**"]),
@@ -45,7 +56,10 @@ filegroup(
         "test-setup.sh",
         "generate-xml.sh",
         "collect_coverage.sh",
-    ] + glob(["LcovMerger/**"]),
+    ] + glob(["LcovMerger/**"]) + select({
+        "@bazel_tools//src/conditions:windows": ["test_wrapper"],
+        "//conditions:default": [],
+    }),
     visibility = ["//tools:__pkg__"],
 )
 

tools/test/BUILD.tools

@@ -32,3 +32,11 @@ filegroup(
     name = "coverage_report_generator",
     srcs = ["@bazel_tools//tools/test/LcovMerger/java/com/google/devtools/lcovmerger:Main"],
 )
+
+filegroup(
+    name = "test_wrapper",
+    srcs = select({
+        "@bazel_tools//src/conditions:windows": ["test_wrapper.exe"],
+        "//conditions:default": ["test_wrapper"],
+    }),
+)

tools/test/windows/dummy.cc

@@ -0,0 +1,27 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Empty implementation of the test wrapper.
+//
+// As of 2018-08-06, every platform uses //tools/test:test-setup.sh as the test
+// wrapper, and we are working on introducing a C++ test wrapper for Windows.
+// See https://github.com/laszlocsomor/proposals/blob/win-test-runner/designs/2018-07-18-windows-native-test-runner.md
+
+#include <stdio.h>
+
+int main(int, char**) {
+  fprintf(stderr,
+          __FILE__ ": The C++ test wrapper is not used on this platform.\n");
+  return 1;
+}

tools/test/windows/test_wrapper.cc

@@ -0,0 +1,22 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Test wrapper implementation for Windows.
+// Design: https://github.com/laszlocsomor/proposals/blob/win-test-runner/designs/2018-07-18-windows-native-test-runner.md
+
+int main(int argc, char** argv) {
+  // TODO(laszlocsomor): Implement the functionality described in
+  // https://github.com/laszlocsomor/proposals/blob/win-test-runner/designs/2018-07-18-windows-native-test-runner.md
+  return 0;
+}