# Copyright 2018 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/testing/test_spec.gni")

# Defines a Rust unit test, without also compiling a separate binary or library
# target.
#
# Parameters
#
#   name
#     Name of the test binary, also used as the crate name as defined in its
#     manifest file. If not specified, it is assumed to be the same as the
#     target name.
#
#   version
#     Semver version of the crate as seen on crates.io.
#
#   edition (optional)
#     Edition of the Rust language to be used.
#     Options are "2015" and "2018". Defaults to "2018".
#
#   configs (optional)
#     A list of config labels applying to this target.
#
#   deps (optional)
#     List of rust_library GN targets on which this crate depends.
#     Third party crates can be included through paths like
#     "//third_party/rust_crates:<cratename>",
#
#   non_rust_deps (optional)
#     List of non-rust_library GN targets on which this crate depends.
#
#   test_environments (optional)
#     What environments the unit test should target. Only used here
#     for linux and mac tests, with a default value of a general linux/mac
#     environment (as a function of $current_os).
#     See environments parameter on //build/testing/test_spec.gni for more
#     details.

#   args (optional)
#     List of flags to pass directly to the test binary, e.g.
#     ["--nocapture"].
#
#   source_root (optional)
#     Location of the crate root (e.g. `src/main.rs` or `src/lib.rs`).
#     This should usually be 'src/lib.rs/ for libraries (the default)
#     and `src/main.rs` for binaries.
#
#   features (optional)
#     A list of conditional compilation flags to enable. This can be used to set features for crates
#     built in-tree which are also published to crates.io. This would be passed to rustc as
#     '--cfg feature=XXX'
#
# Example of usage:
#
#   rustc_test("foo_test") {
#     source_root = "src/foo_test.rs",
#     deps = [
#       "//garnet/public/rust/bar",
#       "//third_party/rust_crates:clap",
#       "//third_party/rust_crates:serde",
#       "//third_party/rust_crates:slab",
#     ]
#   }
template("rustc_test") {
  not_needed(invoker,
             [
               "version",
               "edition",
               "force_opt",
               "testonly",
             ])

  # default location for rust libraries
  source_root = "src/lib.rs"
  if (defined(invoker.source_root)) {
    source_root = invoker.source_root
  }

  # use the target name unless another name is specified
  package_name = target_name
  if (defined(invoker.name)) {
    package_name = invoker.name
  }

  # built-in gn rules do not support dashes
  crate_name = string_replace(package_name, "-", "_")

  if (!is_fuchsia) {
    test_output_file = "${root_out_dir}/${crate_name}"
    test_spec_target_name = "${target_name}_spec"
    test_spec(test_spec_target_name) {
      target = ":${invoker.target_name}"
      path = test_output_file

      command = [ rebase_path(test_output_file, root_build_dir) ]

      if (defined(invoker.args)) {
        command += invoker.args
      }

      deps = []
      if (defined(invoker.deps)) {
        deps += invoker.deps
      }
      if (defined(invoker.non_rust_deps)) {
        deps += invoker.non_rust_deps
      }
      if (defined(invoker.test_environments)) {
        environments = invoker.test_environments
      }
    }
  } else {
    # if not a host-side target, we don't need this since it doesn't
    # propogate to package.gni
    not_needed(invoker, [ "test_environments" ])
  }

  # enable these features for the target
  features = []
  if (defined(invoker.features)) {
    foreach(i, invoker.features) {
      features += [ "--cfg=feature=\"${i}\"" ]
    }
  }

  executable(target_name) {
    # anything defined with rustc_test MUST be a test target
    testonly = true

    configs = []
    configs = invoker.configs

    crate_root = source_root
    output_name = crate_name
    crate_name = crate_name

    # tell rustc to compile in the test harness
    rustflags = features + [ "--test" ]

    deps = []
    if (defined(invoker.deps)) {
      deps = invoker.deps
    }
    if (defined(invoker.non_rust_deps)) {
      deps += invoker.non_rust_deps
    }

    # test_deps specified in the parent template (if not used directly)
    # should also be treated as normal dependencies
    if (defined(invoker.test_deps)) {
      deps += invoker.test_deps
    }

    if (is_linux || is_mac) {
      # if this test is being built on host, depend on the test_spec
      deps += [ ":$test_spec_target_name" ]
    }

    if (is_fuchsia) {
      deps += [ "//build/test:rust_test_metadata" ]
      metadata = {
        cmx_patches_walk = [ "//build/test:rust_test_metadata" ]
      }
    }

    if (defined(invoker.edition) && invoker.edition == "2015") {
      configs -= [ "//build/config:rust_edition_2018" ]
      configs += [ "//build/config:rust_edition_2015" ]
    }

    forward_variables_from(invoker, [ "visibility" ])
  }
}