Move Kover agent setup to runtime

kotlin/internal/jvm/impl.bzl

@@ -26,11 +26,10 @@ load(
 )
 load(
     "//kotlin/internal/jvm:kover.bzl",
-    _create_kover_agent_actions = "create_kover_agent_actions",
     _create_kover_metadata_action = "create_kover_metadata_action",
     _get_kover_agent_files = "get_kover_agent_file",
-    _get_kover_jvm_flags = "get_kover_jvm_flags",
     _is_kover_enabled = "is_kover_enabled",
+    _kover_jvm_flags_setup = "kover_jvm_flags_setup",
 )
 load(
     "//kotlin/internal/utils:utils.bzl",
@@ -124,6 +123,7 @@ def _write_launcher_action(ctx, rjars, main_class, jvm_flags):
                 "%set_java_coverage_new_implementation%": """export JAVA_COVERAGE_NEW_IMPLEMENTATION=YES""",
                 "%test_runtime_classpath_file%": "export TEST_RUNTIME_CLASSPATH_FILE=${JAVA_RUNFILES}",
                 "%workspace_prefix%": ctx.workspace_name + "/",
+                "%kover_jvm_flags_setup%": "",
             },
             is_executable = True,
         )
@@ -133,6 +133,30 @@ def _write_launcher_action(ctx, rjars, main_class, jvm_flags):
         ["${RUNPATH}%s" % (j.short_path) for j in rjars.to_list()],
     )
 
+    if ctx.configuration.coverage_enabled and _is_kover_enabled(ctx):
+        kover_agent_files = _get_kover_agent_files(ctx)
+        ctx.actions.expand_template(
+            template = template,
+            output = ctx.outputs.executable,
+            substitutions = {
+                "%classpath%": classpath,
+                "%java_start_class%": main_class,
+                "%javabin%": java_bin,
+                "%jvm_flags%": jvm_flags,
+                "%needs_runfiles%": "0" if _is_absolute(java_bin_path) else "1",
+                "%runfiles_manifest_only%": "",
+                "%set_jacoco_java_runfiles_root%": "",
+                "%set_jacoco_main_class%": "",
+                "%set_jacoco_metadata%": "",
+                "%set_java_coverage_new_implementation%": """export JAVA_COVERAGE_NEW_IMPLEMENTATION=NO""",
+                "%test_runtime_classpath_file%": "export TEST_RUNTIME_CLASSPATH_FILE=${JAVA_RUNFILES}",
+                "%workspace_prefix%": ctx.workspace_name + "/",
+                "%kover_jvm_flags_setup%": _kover_jvm_flags_setup(kover_agent_files, ctx.label.package, ctx.attr.name),
+            },
+            is_executable = True,
+        )
+        return []
+
     ctx.actions.expand_template(
         template = template,
         output = ctx.outputs.executable,
@@ -149,6 +173,7 @@ def _write_launcher_action(ctx, rjars, main_class, jvm_flags):
             "%set_java_coverage_new_implementation%": """export JAVA_COVERAGE_NEW_IMPLEMENTATION=NO""",
             "%test_runtime_classpath_file%": "export TEST_RUNTIME_CLASSPATH_FILE=${JAVA_RUNFILES}",
             "%workspace_prefix%": ctx.workspace_name + "/",
+            "%kover_jvm_flags_setup%": "",
         },
         is_executable = True,
     )
@@ -299,19 +324,13 @@ def kt_jvm_junit_test_impl(ctx):
     if ctx.configuration.coverage_enabled:
         if _is_kover_enabled(ctx):
             kover_agent_files = _get_kover_agent_files(ctx)
-            kover_output_file, kover_args_file = _create_kover_agent_actions(ctx, ctx.attr.name)
             kover_output_metadata_file = _create_kover_metadata_action(
                 ctx,
                 ctx.attr.name,
                 ctx.attr.deps + ctx.attr.associates,
-                kover_output_file,
             )
-            flags = _get_kover_jvm_flags(kover_agent_files, kover_args_file)
-
-            # add Kover agent jvm_flag, inputs and outputs
-            coverage_jvm_flags = [flags]
             coverage_inputs = [depset(kover_agent_files)]
-            coverage_runfiles = [kover_args_file, kover_output_metadata_file]
+            coverage_runfiles = [kover_output_metadata_file]
         else:
             jacocorunner = ctx.toolchains[_TOOLCHAIN_TYPE].jacocorunner
             coverage_runfiles = jacocorunner.files.to_list()

kotlin/internal/jvm/kover.bzl

@@ -75,61 +75,11 @@ def get_kover_agent_file(ctx):
     kover_agent_info = kover_agent[DefaultInfo]
     return kover_agent_info.files.to_list()
 
-def get_kover_jvm_flags(kover_agent_files, kover_args_file):
-    """Compute the jvm flags used to setup Kover agent.
+def kover_jvm_flags_setup(kover_agent_files, pkg, name):
+    """Return the %kover_jvm_flags_setup% substitution — a call to _setup_kover in the template."""
+    return '_setup_kover "%s" "%s" "%s"' % (kover_agent_files[0].short_path, pkg, name)
 
-    Args:
-        kover_agent_files: List of Kover agent files.
-        kover_args_file: The Kover arguments file.
-
-    Returns:
-        The flag string to be used by test runner JVM.
-    """
-    jvm_args = [
-        "-Xbootclasspath/a:%s" % (kover_agent_files[0].short_path),
-        "-javaagent:%s=file:%s" % (kover_agent_files[0].short_path, kover_args_file.short_path),
-    ]
-    return " ".join(jvm_args)
-
-def create_kover_agent_actions(ctx, name):
-    """Generate the actions needed to emit Kover code coverage metadata file.
-
-    Creates the properly populated arguments input file needed by Kover agent.
-
-    Args:
-        ctx: The rule context.
-        name: The name of the target.
-
-    Returns:
-        A tuple of (kover_output_file, kover_args_file).
-    """
-
-    # declare code coverage raw data binary output file
-    binary_output_name = "%s-kover_report.ic" % name
-    kover_output_file = ctx.actions.declare_file(binary_output_name)
-
-    # Hack: there is curently no way to indicate this file will be created Kover agent
-    ctx.actions.run_shell(
-        outputs = [kover_output_file],
-        command = "touch {}".format(kover_output_file.path),
-    )
-
-    # declare args file - https://kotlin.github.io/kotlinx-kover/jvm-agent/#kover-jvm-arguments-file
-    kover_args_file = ctx.actions.declare_file(
-        "%s-kover.args.txt" % name,
-    )
-    ctx.actions.write(
-        kover_args_file,
-        "report.file=../../%s" % binary_output_name,  # Kotlin compiler runs in runfiles folder, make sure file is created is correct location
-    )
-
-    return kover_output_file, kover_args_file
-
-def create_kover_metadata_action(
-        ctx,
-        name,
-        deps,
-        kover_output_file):
+def create_kover_metadata_action(ctx, name, deps):
     """Generate kover metadata file needed for invoking kover CLI to generate report.
 
     More info at: https://kotlin.github.io/kotlinx-kover/cli/
@@ -138,7 +88,6 @@ def create_kover_metadata_action(
         ctx: The rule context.
         name: The name of the target.
         deps: The dependencies to collect coverage for.
-        kover_output_file: The Kover output file.
 
     Returns:
         The kover output metadata file.
@@ -177,8 +126,6 @@ def create_kover_metadata_action(
         excludes.extend(["--excludeInheritedFrom", exclude_inherited_from])
 
     ctx.actions.write(kover_output_metadata_file, "\n".join([
-        "report",
-        kover_output_file.path,
         "--title",
         "Code-Coverage Analysis: %s" % ctx.label,
     ] + srcs + classfiles + excludes))

kotlin/internal/jvm/kt_android_local_test_impl.bzl

@@ -76,11 +76,10 @@ load(
 )
 load(
     "//kotlin/internal/jvm:kover.bzl",
-    _create_kover_agent_actions = "create_kover_agent_actions",
     _create_kover_metadata_action = "create_kover_metadata_action",
     _get_kover_agent_files = "get_kover_agent_file",
-    _get_kover_jvm_flags = "get_kover_jvm_flags",
     _is_kover_enabled = "is_kover_enabled",
+    _kover_jvm_flags_setup = "kover_jvm_flags_setup",
 )
 
 _JACOCOCO_CLASS = "com.google.testing.coverage.JacocoCoverageRunner"
@@ -142,18 +141,13 @@ def _process_jvm(ctx, resources_ctx, **_unused_sub_ctxs):
     if ctx.configuration.coverage_enabled:
         if _is_kover_enabled(ctx):
             kover_agent_files = _get_kover_agent_files(ctx)
-            kover_output_file, kover_args_file = _create_kover_agent_actions(ctx, ctx.attr.name)
             kover_output_metadata_file = _create_kover_metadata_action(
                 ctx,
                 ctx.attr.name,
                 ctx.attr.deps + ctx.attr.associates,
-                kover_output_file,
             )
 
-            flags = _get_kover_jvm_flags(kover_agent_files, kover_args_file)
-            jvm_flags.append(flags)
-
-            transitive.extend([depset(kover_agent_files), depset([kover_args_file]), depset([kover_output_metadata_file])])
+            transitive.extend([depset(kover_agent_files), depset([kover_output_metadata_file])])
 
             java_start_class = ctx.attr.main_class
             coverage_start_class = None
@@ -336,10 +330,16 @@ def _create_stub(
         subs["%set_jacoco_main_class%"] = ""
         subs["%set_jacoco_java_runfiles_root%"] = ""
 
+    if ctx.configuration.coverage_enabled and _is_kover_enabled(ctx):
+        kover_agent_files = _get_kover_agent_files(ctx)
+        subs["%kover_jvm_flags_setup%"] = _kover_jvm_flags_setup(kover_agent_files, ctx.label.package, ctx.attr.name)
+    else:
+        subs["%kover_jvm_flags_setup%"] = ""
+
     subs.update(substitutes)
 
     ctx.actions.expand_template(
-        template = _utils.only(_get_android_toolchain(ctx).java_stub.files.to_list()),
+        template = ctx.attr.java_stub_template.files.to_list()[0],
         output = stub_file,
         substitutions = subs,
         is_executable = True,

src/test/starlark/internal/jvm/kover_test.bzl

@@ -15,45 +15,41 @@
 """Tests for Kover code coverage integration."""
 
 load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
-load("//kotlin/internal/jvm:kover.bzl", "get_kover_jvm_flags")
+load("//kotlin/internal/jvm:kover.bzl", "kover_jvm_flags_setup")
 
-def _get_kover_jvm_flags_test_impl(ctx):
-    """Test that get_kover_jvm_flags generates correct JVM agent flags including bootclasspath."""
+def _kover_jvm_flags_setup_test_impl(ctx):
+    """Test that kover_jvm_flags_setup emits the _setup_kover shell call with agent path, package and name."""
     env = unittest.begin(ctx)
 
-    # Create mock file objects with short_path attribute
+    # Create a mock agent file object with a short_path attribute.
     mock_agent_file = struct(short_path = "external/kover/kover-jvm-agent.jar")
-    mock_args_file = struct(short_path = "bazel-out/k8-fastbuild/bin/test-kover.args.txt")
 
-    result = get_kover_jvm_flags([mock_agent_file], mock_args_file)
+    result = kover_jvm_flags_setup([mock_agent_file], "path/to/pkg", "my_test")
 
-    # Expected format includes both -Xbootclasspath/a and -javaagent flags
-    expected = "-Xbootclasspath/a:external/kover/kover-jvm-agent.jar -javaagent:external/kover/kover-jvm-agent.jar=file:bazel-out/k8-fastbuild/bin/test-kover.args.txt"
+    expected = '_setup_kover "external/kover/kover-jvm-agent.jar" "path/to/pkg" "my_test"'
     asserts.equals(env, expected, result)
 
     return unittest.end(env)
 
-get_kover_jvm_flags_test = unittest.make(_get_kover_jvm_flags_test_impl)
+_kover_jvm_flags_setup_test = unittest.make(_kover_jvm_flags_setup_test_impl)
 
-def _kover_jvm_flags_format_test_impl(ctx):
-    """Test JVM flags format with different path patterns."""
+def _kover_jvm_flags_setup_format_test_impl(ctx):
+    """Test the kover_jvm_flags_setup call format with different path patterns."""
     env = unittest.begin(ctx)
 
-    # Test with workspace-relative path
     mock_agent = struct(short_path = "maven/kover-agent-1.0.jar")
-    mock_args = struct(short_path = "pkg/test.args")
 
-    result = get_kover_jvm_flags([mock_agent], mock_args)
+    result = kover_jvm_flags_setup([mock_agent], "pkg", "test")
 
-    # Verify the format includes both bootclasspath and javaagent flags
-    asserts.true(env, "-Xbootclasspath/a:" in result)
-    asserts.true(env, "-javaagent:" in result)
-    asserts.true(env, "=file:" in result)
-    asserts.true(env, result.endswith("pkg/test.args"))
+    # Verify the call uses the first agent file and quotes all three arguments.
+    asserts.true(env, result.startswith("_setup_kover "))
+    asserts.true(env, '"maven/kover-agent-1.0.jar"' in result)
+    asserts.true(env, '"pkg"' in result)
+    asserts.true(env, result.endswith('"test"'))
 
     return unittest.end(env)
 
-kover_jvm_flags_format_test = unittest.make(_kover_jvm_flags_format_test_impl)
+_kover_jvm_flags_setup_format_test = unittest.make(_kover_jvm_flags_setup_format_test_impl)
 
 def kover_test_suite(name):
     """Create the test suite for Kover integration tests.
@@ -63,6 +59,6 @@ def kover_test_suite(name):
     """
     unittest.suite(
         name,
-        get_kover_jvm_flags_test,
-        kover_jvm_flags_format_test,
+        _kover_jvm_flags_setup_test,
+        _kover_jvm_flags_setup_format_test,
     )

third_party/java_stub_template.txt

@@ -292,6 +292,17 @@ if [[ -n "$TEST_TMPDIR" && -d "$TEST_TMPDIR" ]]; then
   JVM_FLAGS+=" -Djava.io.tmpdir=$TEST_TMPDIR"
 fi
 
+function _setup_kover() {
+  local agent="$1" pkg="$2" name="$3"
+  local ic
+  ic=$(mktemp)
+  mkdir -p "${TEST_UNDECLARED_OUTPUTS_DIR}/${pkg}"
+  echo "report.file=${TEST_UNDECLARED_OUTPUTS_DIR}/${pkg}/${name}-kover_report.ic" > "$ic"
+  JVM_FLAGS="${JVM_FLAGS} -Xbootclasspath/a:${agent} -javaagent:${agent}=file:${ic}"
+}
+
+%kover_jvm_flags_setup%
+
 ARGS=(
   ${JVM_DEBUG_FLAGS}
   ${JVM_FLAGS}