Set default value for --experimental_build_event_output_group_mode to inline

coverage artifacts in `TargetComplete` events.

RELNOTES: By default, coverage artifacts will be reported inline in the
`TargetComplete` event. To disable this behavior, pass
`--experimental_build_event_output_group_mode=baseline.lcov=named_set_of_files_only`.
PiperOrigin-RevId: 671442846
Change-Id: Id91e6c53cdc04d527b45a8c10bee833cbfc64b63

Author: michaeledgar

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

@@ -594,8 +594,8 @@ private static OutputGroup makeOutputGroupProto(
     OutputGroupFileMode fileMode = converters.getFileModeForOutputGroup(outputGroup);
     if (fileMode == OutputGroupFileMode.NAMED_SET_OF_FILES_ONLY
         || fileMode == OutputGroupFileMode.BOTH) {
-      ArtifactGroupNamer namer2 = converters.artifactGroupNamer();
-      builder.addFileSets(namer2.apply(artifactsToReport.get().toNode()));
+      ArtifactGroupNamer namer = converters.artifactGroupNamer();
+      builder.addFileSets(namer.apply(artifactsToReport.get().toNode()));
     }
     if (fileMode == OutputGroupFileMode.INLINE_ONLY || fileMode == OutputGroupFileMode.BOTH) {
       addFilesDirectlyToProtoField(

src/main/java/com/google/devtools/build/lib/buildeventstream/BuildEventProtocolOptions.java

@@ -163,10 +163,16 @@ public interface OutputGroupFileModes {
    * Collects the values in {@link #outputGroupFileModes} into a map and returns a {@link
    * OutputGroupFileModes} backed by that map and defaulting to {@link
    * OutputGroupFileMode.NAMED_SET_OF_FILES_ONLY} for out groups not in that map.
+   *
+   * <p>This also implements the default value of the {@code
+   * --experimental_build_event_output_group_mode} option, which as an {@code allowMultiple} option
+   * cannot specify a default value. The default value sets the mode for coverage artifacts to BOTH:
+   * {@code --experimental_build_event_output_group_mode=baseline.lcov=both}.
    */
   public OutputGroupFileModes getOutputGroupFileModesMapping() {
     var modeMap =
         ImmutableMap.<String, OutputGroupFileMode>builder()
+            .put(TestFileNameConstants.BASELINE_COVERAGE, OutputGroupFileMode.BOTH)
             .putAll(outputGroupFileModes)
             .buildKeepingLast();
     return (outputGroup) ->
@@ -185,6 +191,7 @@ public OutputGroupFileModes getOutputGroupFileModesMapping() {
               + " BEP events. Values are an assignment of an output group name to one of"
               + " 'NAMED_SET_OF_FILES_ONLY', 'INLINE_ONLY', or 'BOTH'. The default value is"
               + " 'NAMED_SET_OF_FILES_ONLY'. If an output group is repeated, the final value to"
-              + " appear is used.")
+              + " appear is used. The default value sets the mode for coverage artifacts to BOTH: "
+              + "--experimental_build_event_output_group_mode=baseline.lcov=both")
   public List<Map.Entry<String, OutputGroupFileMode>> outputGroupFileModes;
 }

src/test/shell/bazel/bazel_coverage_cc_test_gcc.sh

@@ -78,9 +78,9 @@ function test_cc_test_coverage_gcov() {
     echo "Skipping test." && return
   fi
   setup_a_cc_lib_and_t_cc_test
-
+  BEP=bep.txt
   bazel coverage  --test_output=all \
-     --build_event_text_file=bep.txt //:t &>"$TEST_log" \
+     --build_event_text_file="${BEP}" //:t &>"$TEST_log" \
      || fail "Coverage for //:t failed"
 
   local coverage_file_path="$( get_coverage_file_path_from_test_log )"
@@ -109,12 +109,22 @@ end_of_record"
 
   # Verify that this is also true for cached coverage actions.
   bazel coverage  --test_output=all \
-      --build_event_text_file=bep.txt //:t \
+      --build_event_text_file="${BEP}" //:t \
       &>"$TEST_log" || fail "Coverage for //:t failed"
   expect_log '//:t.*cached'
   # Verify the files are reported correctly in the build event protocol.
-  assert_contains 'name: "test.lcov"' bep.txt
-  assert_contains 'name: "baseline.lcov"' bep.txt
+  assert_contains 'name: "test.lcov"' "${BEP}"
+  assert_contains 'name: "baseline.lcov"' "${BEP}"
+    # Assert coverage output is reported in the right proto fields
+  grep 'name: "baseline.lcov"' -B1 "${BEP}" | grep -q 'output_group'\
+    || fail "File 'baseline.lcov' missing in output_group!"
+  grep 'name: "t/baseline_coverage.dat"' -B1 "${BEP}"\
+    | grep -q 'inline_files'\
+    || fail "File 'baseline_coverage.dat' missing in inline_files!"
+  grep 'name: "baseline.lcov"' -B1 "${BEP}" | grep -q 'important_output'\
+    || fail "File 'baseline.lcov' missing in important_output!"
+  grep 'name: "test.lcov"' -B1 "${BEP}" | grep -q 'test_action_output'\
+    || fail "File 'test.lcov' missing in test_action_output!"
 }
 
 # TODO(#6254): Enable this test when #6254 is fixed.