Add support for $(location) in nodejs_binary#entry_point

Fixes bazel-contrib#32

README.md

@@ -106,7 +106,7 @@ nodejs_binary(
         "@//:node_modules",
         "main.js",
     ],
-    entry_point = "workspace_name/main.js",
+    entry_point = "$(location :main.js)",
     args = ["--node_options=--expose-gc"],
 )
 ```

examples/program/BUILD.bazel

@@ -1,4 +1,18 @@
-load("@build_bazel_rules_nodejs//:defs.bzl", "jasmine_node_test")
+# Copyright 2017 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("@build_bazel_rules_nodejs//:defs.bzl", "jasmine_node_test", "nodejs_binary")
 load("@build_bazel_rules_nodejs//:internal/typescript_mock.bzl", "mock_typescript_lib")
 
 # Make the jasmine library available at runtime by exposing our node_modules
@@ -13,21 +27,51 @@ filegroup(
     visibility = ["//visibility:public"],
 )
 
+# Mock out the ts_library rule from rules_typescript
+# We want to test that TypeScript outputs can be used in nodejs rules, but
+# don't want a cyclical dependency between this repository and rules_typescript.
 mock_typescript_lib(
     name = "mock_ts_lib",
     srcs = ["decrement.js"],
 )
 
-# This is like a "js_library", but there are no actions to run on JS files so a
-# filegroup is semantically equivalent.
-filegroup(
-    name = "program",
-    srcs = ["index.js"],
+# This binary wraps up our program in a way that can be `bazel run`, and also
+# produces a .exe file on Windows.
+nodejs_binary(
+    name = "bin",
+    # The script we'll ask node to run
+    # Note: the label given here must exactly match an entry in "data"
+    entry_point = "$(location :index.js)",
+    # Runtime dependencies, in our case the script is standalone.
+    data = [":index.js"],
+    # Only needed because we'll typically run this binary from the workspace
+    # in the parent directory. The default value for `node_modules` is
+    # @//:node_modules, where the leading @ means "the workspace where the user
+    # runs the target"
+    node_modules = "//:node_modules",
 )
 
+# Unit tests for the files in the package.
+# Convenient to use with `ibazel test`
 jasmine_node_test(
     name = "test",
+    # The typical Bazel idiom is for srcs to be the files directly consumed.
+    # In the case of a unit test, that's the spec files.
+    # See https://docs.bazel.build/versions/master/build-ref.html#types_of_dependencies
     srcs = glob(["*.spec.js"]),
-    deps = [":program", ":mock_ts_lib"],
-    node_modules = "//:node_modules"
+    # The deps is the runtime dependencies. These can point to compiled files
+    # such as the TypeScript library we mocked out.
+    deps = [":index.js", ":mock_ts_lib"],
+    # See comment about node_modules above.
+    node_modules = "//:node_modules",
+)
+
+# An end-to-end test for the program.
+# It's written in Python just because this is convenient and cross-platform.
+# See https://docs.bazel.build/versions/master/be/python.html#py_test
+py_test(
+    name = "bin_test",
+    srcs = ["bin_test.py"],
+    deps = ["@build_bazel_rules_nodejs//internal:runfiles"],
+    data = [":bin"],
 )

examples/program/bin_test.py

@@ -0,0 +1,23 @@
+"""End-to-end test for a nodejs_binary
+
+Simply find the binary and run it, asserting that it produces correct output.
+"""
+
+from subprocess import check_output
+from sys import platform
+import unittest
+
+from build_bazel_rules_nodejs.internal.runfiles import resolve_runfile
+
+class BinTest(unittest.TestCase):
+
+  def testRuns(self):
+    if platform == "win32" or platform == "win64":
+      program = 'program_example/bin.exe'
+    else:
+      program = 'program_example/bin'
+    actual = check_output([resolve_runfile(program)])
+    self.assertEqual(actual, '2\n')
+
+if __name__ == '__main__':
+  unittest.main()

examples/program/index.js

@@ -3,3 +3,7 @@ function increment(n) {
 }
 
 exports.increment = increment;
+
+if (require.main === module) {
+  console.log(increment(1));
+}

internal/BUILD.bazel

@@ -16,9 +16,15 @@ package(default_visibility = ["//visibility:public"])
 
 exports_files(["node_launcher.sh", "node_loader.js", "jasmine_runner.js"])
 
+py_library(
+    name = "runfiles",
+    srcs = ["runfiles.py"],
+)
+
 py_test(
     name = "check_bazel_version_test",
     srcs = ["check_bazel_version_test.py"],
+    deps = [":runfiles"],
     data = [":check_bazel_version.bzl"],
     size = "small",
 )

internal/check_bazel_version_test.py

@@ -1,17 +1,5 @@
-import os
 import unittest
-
-def resolve_runfile(path):
-  if os.getenv('RUNFILES_MANIFEST_ONLY') != "1":
-    return os.path.join(os.environ['TEST_SRCDIR'], path)
-
-  manifest = os.getenv('RUNFILES_MANIFEST_FILE')
-  with open(manifest) as f:
-    for line in f.readlines():
-      if line.split()[0] == path:
-        return line.split()[1]
-  raise "Cannot find %s in manifest %s" % (path, manifest)
-
+from runfiles import resolve_runfile
 
 class MockSkylark:
   """A class that returns mocked bazel version and fail().

internal/jasmine_node_test.bzl

@@ -8,15 +8,16 @@ def jasmine_node_test(name, srcs, data = [], deps = [], **kwargs):
       testonly = 1,
   )
 
-  all_data = data + srcs + deps
-  all_data += [Label("//internal:jasmine_runner.js")]
-  all_data += [":%s_devmode_srcs.MF" % name]
-  entry_point = "build_bazel_rules_nodejs/internal/jasmine_runner.js"
+  runner_js = "@build_bazel_rules_nodejs//internal:jasmine_runner.js"
+  all_data = data + srcs + deps + [
+      runner_js,
+      ":%s_devmode_srcs.MF" % name,
+  ]
 
   nodejs_test(
       name = name,
       data = all_data,
-      entry_point = entry_point,
+      entry_point = "$(location %s)" % runner_js,
       templated_args = ["$(location :%s_devmode_srcs.MF)" % name],
       testonly = 1,
       **kwargs

internal/node.bzl

@@ -51,7 +51,7 @@ def _write_loader_script(ctx):
       output=ctx.outputs.loader,
       substitutions={
           "TEMPLATED_module_roots": "\n  " + ",\n  ".join(module_mappings),
-          "TEMPLATED_entry_point": ctx.attr.entry_point,
+          "TEMPLATED_entry_point": expand_location_into_runfiles(ctx, ctx.attr.entry_point),
           "TEMPLATED_label_package": ctx.attr.node_modules.label.package,
           # If the label being built is in another workspace, look for runfiles
           # produced by that workspace

internal/runfiles.py

@@ -0,0 +1,12 @@
+import os
+
+def resolve_runfile(path):
+  if os.getenv('RUNFILES_MANIFEST_ONLY') != "1":
+    return os.path.join(os.environ['TEST_SRCDIR'], path)
+
+  manifest = os.getenv('RUNFILES_MANIFEST_FILE')
+  with open(manifest) as f:
+    for line in f.readlines():
+      if line.split()[0] == path:
+        return line.split()[1]
+  raise "Cannot find %s in manifest %s" % (path, manifest)