Testing toolchain and Junit deps (bazelbuild#1102)

* Add testing toolchain with Junit deps

* Add docs for junit

* Update junit related aspect test deps

docs/testing.md

@@ -0,0 +1,45 @@
+## Testing toolchain configuration
+
+Toolchain type `testing_toolchain_type` is used to set up test dependencies. 
+
+### Example to set up JUnit dependencies
+
+`BUILD` file content in your prefered package:
+```starlark
+load("@io_bazel_rules_scala//scala:providers.bzl", "declare_deps_provider")
+load("@io_bazel_rules_scala//testing/toolchain:toolchain.bzl", "scala_testing_toolchain")
+
+scala_testing_toolchain(
+    name = "testing_toolchains_with_junit",
+    dep_providers = [
+        ":junit_classpath_provider",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+toolchain(
+    name = "testing_toolchain",
+    toolchain = ":testing_toolchains_with_junit",
+    toolchain_type = "@io_bazel_rules_scala//testing/toolchain:testing_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
+declare_deps_provider(
+    name = "junit_classpath_provider",
+    deps_id = "junit_classpath",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@my_hamcrest_core",
+        "@my_junit",
+    ],
+)
+```
+
+`junit_classpath_provider` (deps_id `junit_classpath`) is where classpath required for junit tests
+is defined.
+
+Toolchain must be registerd in your `WORKSPACE` file: 
+```starlark
+register_toolchains('//my/package:testing_toolchain')
+```
+

junit/junit.bzl

@@ -31,3 +31,5 @@ def junit_repositories(maven_servers = _default_maven_server_urls()):
         name = "io_bazel_rules_scala/dependency/hamcrest/hamcrest_core",
         actual = "@io_bazel_rules_scala_org_hamcrest_hamcrest_core//jar",
     )
+
+    native.register_toolchains("@io_bazel_rules_scala//testing:testing_toolchain")

scala/private/phases/phase_collect_jars.bzl

@@ -33,8 +33,7 @@ def phase_collect_jars_macro_library(ctx, p):
 def phase_collect_jars_junit_test(ctx, p):
     args = struct(
         extra_deps = [
-            ctx.attr._junit,
-            ctx.attr._hamcrest,
+            ctx.attr._junit_classpath,
             ctx.attr.suite_label,
             ctx.attr._bazel_test_runner,
         ],

scala/private/phases/phase_compile.bzl

@@ -62,16 +62,14 @@ def phase_compile_junit_test(ctx, p):
     args = struct(
         buildijar = False,
         implicit_junit_deps_needed_for_java_compilation = [
-            ctx.attr._junit,
-            ctx.attr._hamcrest,
+            ctx.attr._junit_classpath,
         ],
         unused_dependency_checker_ignored_targets = [
             target.label
             for target in p.scalac_provider.default_classpath +
                           ctx.attr.unused_dependency_checker_ignored_targets
         ] + [
-            ctx.attr._junit.label,
-            ctx.attr._hamcrest.label,
+            ctx.attr._junit_classpath.label,
             ctx.attr.suite_label.label,
             ctx.attr._bazel_test_runner.label,
         ],

scala/private/rules/scala_junit_test.bzl

@@ -69,15 +69,8 @@ _scala_junit_test_attrs = {
         mandatory = False,
     ),
     "jvm_flags": attr.string_list(),
-    "_junit": attr.label(
-        default = Label(
-            "//external:io_bazel_rules_scala/dependency/junit/junit",
-        ),
-    ),
-    "_hamcrest": attr.label(
-        default = Label(
-            "//external:io_bazel_rules_scala/dependency/hamcrest/hamcrest_core",
-        ),
+    "_junit_classpath": attr.label(
+        default = Label("@io_bazel_rules_scala//testing/toolchain:junit_classpath"),
     ),
     "_bazel_test_runner": attr.label(
         default = Label(
@@ -93,10 +86,7 @@ _junit_resolve_deps = {
             Label(
                 "@io_bazel_rules_scala//scala/private/toolchain_deps:scala_library_classpath",
             ),
-            Label("//external:io_bazel_rules_scala/dependency/junit/junit"),
-            Label(
-                "//external:io_bazel_rules_scala/dependency/hamcrest/hamcrest_core",
-            ),
+            Label("@io_bazel_rules_scala//testing/toolchain:junit_classpath"),
         ],
         allow_files = False,
     ),

src/java/io/bazel/rulesscala/test_discovery/BUILD

@@ -7,5 +7,5 @@ scala_library(
         "FilteredRunnerBuilder.scala",
     ],
     visibility = ["//visibility:public"],
-    deps = ["//external:io_bazel_rules_scala/dependency/junit/junit"],
+    deps = ["@io_bazel_rules_scala//testing/toolchain:junit_classpath"],
 )

test/aspect/aspect.bzl

@@ -33,14 +33,12 @@ def _rule_impl(ctx):
         "scala_junit_test": [
             "//test/aspect:scala_junit_test",
             "//scala/private/toolchain_deps:scala_library_classpath",
-            "@io_bazel_rules_scala_junit_junit//:io_bazel_rules_scala_junit_junit",
-            "@io_bazel_rules_scala_org_hamcrest_hamcrest_core//:io_bazel_rules_scala_org_hamcrest_hamcrest_core",
+            "//testing/toolchain:junit_classpath",
         ],
         "scala_specs2_junit_test": [
             "//scala/private/toolchain_deps:scala_library_classpath",
             "//test/aspect:scala_specs2_junit_test",
-            "@io_bazel_rules_scala_junit_junit//:io_bazel_rules_scala_junit_junit",
-            "@io_bazel_rules_scala_org_hamcrest_hamcrest_core//:io_bazel_rules_scala_org_hamcrest_hamcrest_core",
+            "//testing/toolchain:junit_classpath",
             # From specs2/specs2.bzl:specs2_dependencies()
             "@io_bazel_rules_scala//specs2:specs2",
             "@io_bazel_rules_scala_org_specs2_specs2_common//:io_bazel_rules_scala_org_specs2_specs2_common",

testing/BUILD

@@ -0,0 +1,27 @@
+load("@io_bazel_rules_scala//scala:providers.bzl", "declare_deps_provider")
+load("@io_bazel_rules_scala//testing/toolchain:toolchain.bzl", "scala_testing_toolchain")
+
+scala_testing_toolchain(
+    name = "testing_toolchains_with_all_deps_impl",
+    dep_providers = [
+        ":junit_classpath_provider",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+toolchain(
+    name = "testing_toolchain",
+    toolchain = ":testing_toolchains_with_all_deps_impl",
+    toolchain_type = "@io_bazel_rules_scala//testing/toolchain:testing_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
+declare_deps_provider(
+    name = "junit_classpath_provider",
+    deps_id = "junit_classpath",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//external:io_bazel_rules_scala/dependency/hamcrest/hamcrest_core",
+        "//external:io_bazel_rules_scala/dependency/junit/junit",
+    ],
+)

testing/toolchain/BUILD

@@ -0,0 +1,12 @@
+load("@io_bazel_rules_scala//testing/toolchain:toolchain_deps.bzl", "testing_toolchain_deps")
+
+toolchain_type(
+    name = "testing_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
+testing_toolchain_deps(
+    name = "junit_classpath",
+    deps_id = "junit_classpath",
+    visibility = ["//visibility:public"],
+)

testing/toolchain/toolchain.bzl

@@ -0,0 +1,18 @@
+load("//scala:providers.bzl", _DepsInfo = "DepsInfo")
+
+def _scala_toolchain_impl(ctx):
+    toolchain = platform_common.ToolchainInfo(
+        dep_providers = ctx.attr.dep_providers,
+    )
+    return [toolchain]
+
+scala_testing_toolchain = rule(
+    _scala_toolchain_impl,
+    attrs = {
+        "dep_providers": attr.label_list(
+            default = [
+            ],
+            providers = [_DepsInfo],
+        ),
+    },
+)

testing/toolchain/toolchain_deps.bzl

@@ -0,0 +1,18 @@
+load(
+    "//scala/private/toolchain_deps:toolchain_deps.bzl",
+    "expose_toolchain_deps",
+    "java_info_for_deps",
+)
+
+_toolchain_type = "@io_bazel_rules_scala//testing/toolchain:testing_toolchain_type"
+
+def _testing_toolchain_deps(ctx):
+    return expose_toolchain_deps(ctx, _toolchain_type)
+
+testing_toolchain_deps = rule(
+    implementation = _testing_toolchain_deps,
+    attrs = {
+        "deps_id": attr.string(mandatory = True),
+    },
+    toolchains = [_toolchain_type],
+)