coverage: force test's data executable to disable coverage (#10793)

Some of our tests depend on go_binary clis.
Under coverage mode, these clis are mistakenly treated as test binaries
and refused to run without specific environment variables.

Apply a transition on these go_binary to disable coverage, force opt
mode and exec configuration.

Author: sluongng

cli/testutil/testcli/BUILD

@@ -1,16 +1,17 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("//rules:coverage_transitions.bzl", "coverage_free_tool")
 
 package(default_visibility = ["//cli:__subpackages__"])
 
 go_library(
     name = "testcli",
     testonly = 1,
     srcs = ["testcli.go"],
-    data = ["//cli/cmd/bb"],
+    data = [":bb_no_cov"],
     importpath = "github.com/buildbuddy-io/buildbuddy/cli/testutil/testcli",
     visibility = ["//visibility:public"],
     x_defs = {
-        "bbRunfilePath": "$(rlocationpath //cli/cmd/bb)",
+        "bbRunfilePath": "$(rlocationpath :bb_no_cov)",
     },
     deps = [
         "//cli/storage",
@@ -24,3 +25,9 @@ go_library(
         "@com_github_stretchr_testify//require",
     ],
 )
+
+coverage_free_tool(
+    name = "bb_no_cov",
+    tags = ["manual"],
+    target = "//cli/cmd/bb",
+)

enterprise/server/remote_execution/commandutil/BUILD

@@ -37,13 +37,13 @@ go_test(
     ],
     data = select({
         "@io_bazel_rules_go//go/platform:windows": [],
-        "//conditions:default": ["//enterprise/server/remote_execution/commandutil/test_binary"],
+        "//conditions:default": ["//enterprise/server/remote_execution/commandutil/test_binary:test_binary_no_cov"],
     }),
     tags = ["cpu:4"],
     x_defs = select({
         "@io_bazel_rules_go//go/platform:windows": {},
         "//conditions:default": {
-            "testBinaryRunfilePath": "$(rlocationpath //enterprise/server/remote_execution/commandutil/test_binary)",
+            "testBinaryRunfilePath": "$(rlocationpath //enterprise/server/remote_execution/commandutil/test_binary:test_binary_no_cov)",
         },
     }),
     deps = [

enterprise/server/remote_execution/commandutil/test_binary/BUILD

@@ -1,4 +1,5 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+load("//rules:coverage_transitions.bzl", "coverage_free_tool")
 
 package(
     default_testonly = 1,
@@ -15,3 +16,9 @@ go_binary(
     name = "test_binary",
     embed = [":lib"],
 )
+
+coverage_free_tool(
+    name = "test_binary_no_cov",
+    tags = ["manual"],
+    target = ":test_binary",
+)

rules/coverage_transitions.bzl

@@ -0,0 +1,56 @@
+"""Transition helpers used to build tools without coverage instrumentation.
+
+The coverage runner builds every target with coverage enabled, which breaks
+Go binaries that are used as helper tools inside tests (they print coverage
+warnings and behave like test binaries). The transition below disables coverage
+and forces an opt build for those binaries so they behave like normal tools.
+"""
+
+def _coverage_free_exec_transition_impl(settings, attr):
+    return {
+        "//command_line_option:collect_code_coverage": "false",
+        "//command_line_option:compilation_mode": "opt",
+    }
+
+# Transition that turns off coverage and forces opt in the transitioned config.
+coverage_free_exec_transition = transition(
+    implementation = _coverage_free_exec_transition_impl,
+    inputs = [],
+    outputs = [
+        "//command_line_option:collect_code_coverage",
+        "//command_line_option:compilation_mode",
+    ],
+)
+
+def _coverage_free_tool_impl(ctx):
+    target = ctx.attr.target
+    if type(target) == type([]):
+        target = target[0]
+    default = target[DefaultInfo]
+
+    runfiles = default.default_runfiles.merge(default.data_runfiles)
+
+    return [
+        DefaultInfo(
+            files = default.files,
+            data_runfiles = runfiles,
+            default_runfiles = runfiles,
+        ),
+    ]
+
+# Wrapper rule that rebuilds the given executable with the coverage-free
+# transition, exposing identical runfiles for use in data attributes. The rule
+# itself transitions to disable coverage/opt builds, and the wrapped target is
+# built in the execution configuration so the resulting binary matches the
+# executor platform.
+coverage_free_tool = rule(
+    implementation = _coverage_free_tool_impl,
+    attrs = {
+        "target": attr.label(
+            cfg = coverage_free_exec_transition,
+            executable = True,
+            mandatory = True,
+            providers = [DefaultInfo],
+        ),
+    },
+)