feat: add alias targets for unversioned reference to direct deps

Also add starlark unit testing for translate_package_lock as it's going to get more complex.

WORKSPACE

@@ -14,6 +14,10 @@ load("//js:repositories.bzl", "rules_js_dependencies")
 
 rules_js_dependencies()
 
+load("@bazel_skylib//lib:unittest.bzl", "register_unittest_toolchains")
+
+register_unittest_toolchains()
+
 ############################################
 # Gazelle, for generating bzl_library targets
 load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")

js/private/translate_package_lock.bzl

@@ -56,8 +56,17 @@ def _repo_name(package_name, version):
     "Make an external repository name from a package name and a version"
     return "npm_%s-%s" % (_escape(package_name), version)
 
-def _import_dependencies(repository_ctx, bzl_out, packages):
-    for (name, dep) in packages["dependencies"].items():
+def _import_dependencies(lockfile, bzl_out = None):
+    # To allow recursion, accept an optional accumulator
+    # If it's not present, we need to start with the header of the file
+    bzl_out = bzl_out or ["""# @generated by package_lock.bzl from {package_lock}
+
+load("@aspect_rules_js//js:npm_import.bzl", "npm_import")
+
+def npm_repositories():
+    "Define external repositories to fetch each tarball individually from npm on-demand."
+"""]
+    for (name, dep) in lockfile["dependencies"].items():
         if "resolved" not in dep.keys():
             continue
         deps = []
@@ -72,29 +81,57 @@ def _import_dependencies(repository_ctx, bzl_out, packages):
             integrity = dep["integrity"],
             deps = deps,
         )])
+    return bzl_out
+
+def _define_aliases(repository_ctx, lockfile, do_writes = True):
+    # Return value if do_writes = False
+    aliases = {}
+
+    # The lockfile format refers to the context as the package with empty name.
+    # This gives us a way to know which deps the user declared in their package.json
+    # (the direct dependencies).
+    direct = lockfile["packages"][""]
+    direct_names = []
+    direct_names.extend(direct.get("devDependencies", {}).keys())
+    direct_names.extend(direct.get("dependencies", {}).keys())
+
+    for (direct_name, direct_dep) in lockfile["dependencies"].items():
+        if not direct_name in direct_names:
+            continue
+        dep_build_content = """# @generated by package_lock.bzl
+
+alias(name = "{package}", actual = "{actual}", visibility = ["//visibility:public"])
+""".format(
+            package = direct_name.split("/")[-1],
+            actual = "@" + _repo_name(direct_name, direct_dep["version"]),
+        )
+        if do_writes:
+            repository_ctx.file(direct_name + "/BUILD.bazel", dep_build_content)
+        else:
+            # In a starlark unit test, there is no global mutable data structure
+            # that allows us to capture the writes using a mock repository_ctx
+            # so we need a different return type that lets us assert on what's written.
+            # We could do this for production use as well, but then we'd waste memory
+            # in large package-lock.json files holding references to values
+            # we no longer need.
+            aliases[direct_name + "/BUILD.bazel"] = dep_build_content
+    return None if do_writes else aliases
 
 def _translate_package_lock(repository_ctx):
-    bzl_content = ["""# @generated by package_lock.bzl from {package_lock}
-
-load("@aspect_rules_js//js:npm_import.bzl", "npm_import")
-
-def npm_repositories():
-    "Define external repositories to fetch each tarball individually from npm on-demand."
-"""]
-
     lock_content = json.decode(repository_ctx.read(repository_ctx.attr.package_lock))
     lock_version = lock_content["lockfileVersion"]
     if lock_version < 2:
         fail("translate_package_lock only works with npm 7 lockfiles (lockfileVersion >= 2), found %s" % lock_version)
 
-    _import_dependencies(repository_ctx, bzl_content, lock_content)
-
-    repository_ctx.file("repositories.bzl", "\n".join(bzl_content))
+    repository_ctx.file("repositories.bzl", "\n".join(_import_dependencies(lock_content)))
     repository_ctx.file("BUILD.bazel", "")
+    _define_aliases(repository_ctx, lock_content)
 
 translate_package_lock = struct(
     doc = _DOC,
     implementation = _translate_package_lock,
     attrs = _ATTRS,
     repository_name = _repo_name,
+    testonly_import_dependencies = _import_dependencies,
+    testonly_define_aliases = _define_aliases,
 )

js/test/BUILD.bazel

@@ -0,0 +1,3 @@
+load(":translate_package_lock_tests.bzl", "translate_package_lock_tests")
+
+translate_package_lock_tests(name = "test_translate_package_lock")

js/test/translate_package_lock_tests.bzl

@@ -0,0 +1,108 @@
+"""Unit tests for starlark helpers
+
+See https://docs.bazel.build/versions/main/skylark/testing.html#for-testing-starlark-utilities
+"""
+
+load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
+load("//js/private:translate_package_lock.bzl", "translate_package_lock")
+
+_lockfile = json.decode("""
+{
+    "name": "test",
+    "lockfileVersion": 2,
+    "requires": true,
+    "packages": {
+        "": {
+            "devDependencies": {
+                "@gregmagolan/test-b": "^0.0.2"
+            }
+        }
+    },
+    "dependencies": {
+        "@gregmagolan/test-a": {
+            "version": "0.0.1",
+            "resolved": "https://registry.npmjs.org/@gregmagolan/test-a/-/test-a-0.0.1.tgz",
+            "integrity": "sha512-a==",
+            "dev": true
+        },
+        "@gregmagolan/test-b": {
+            "version": "0.0.2",
+            "resolved": "https://registry.npmjs.org/@gregmagolan/test-b/-/test-b-0.0.2.tgz",
+            "integrity": "sha512-b==",
+            "dev": true,
+            "requires": {
+                "@gregmagolan/test-a": "0.0.1"
+            }
+        }
+    }
+}
+""")
+
+def _naming_test_impl(ctx):
+    env = unittest.begin(ctx)
+    asserts.equals(env, "npm_acorn-10.2.3", translate_package_lock.repository_name("acorn", "10.2.3"))
+    asserts.equals(env, "npm__types_node-11.2.3", translate_package_lock.repository_name("@types/node", "11.2.3"))
+    return unittest.end(env)
+
+def _repository_bzl_test_impl(ctx):
+    env = unittest.begin(ctx)
+
+    expected_header = """\
+# @generated by package_lock.bzl from {package_lock}
+
+load("@aspect_rules_js//js:npm_import.bzl", "npm_import")
+
+def npm_repositories():
+    "Define external repositories to fetch each tarball individually from npm on-demand."
+"""
+    expected_a = """\
+    # @generated from [package-lock.json snippet here]
+    npm_import(
+        name = "npm__gregmagolan_test-a-0.0.1",
+        integrity = "sha512-a==",
+        package = "@gregmagolan/test-a",
+        version = "0.0.1",
+        deps = [],
+    )
+"""
+    expected_b = """\
+    # @generated from [package-lock.json snippet here]
+    npm_import(
+        name = "npm__gregmagolan_test-b-0.0.2",
+        integrity = "sha512-b==",
+        package = "@gregmagolan/test-b",
+        version = "0.0.2",
+        deps = ["@npm__gregmagolan_test-a-0.0.1"],
+    )
+"""
+    actual = translate_package_lock.testonly_import_dependencies(_lockfile)
+    asserts.equals(env, 3, len(actual))
+    asserts.equals(env, expected_header, actual[0])
+    asserts.equals(env, expected_a, actual[1])
+    asserts.equals(env, expected_b, actual[2])
+    return unittest.end(env)
+
+def _aliases_test_impl(ctx):
+    env = unittest.begin(ctx)
+    mock_repository_ctx = struct()
+    actual = translate_package_lock.testonly_define_aliases(mock_repository_ctx, _lockfile, False)
+    asserts.equals(env, 1, len(actual.items()))
+
+    # Note: @gregmagolan/test-a should not appear here since it's only a transitive dependency
+    expected = {
+        "@gregmagolan/test-b/BUILD.bazel": """# @generated by package_lock.bzl
+
+alias(name = "test-b", actual = "@npm__gregmagolan_test-b-0.0.2", visibility = ["//visibility:public"])
+""",
+    }
+    asserts.equals(env, expected, actual)
+    return unittest.end(env)
+
+# The unittest library requires that we export the test cases as named test rules,
+# but their names are arbitrary and don't appear anywhere.
+t0_test = unittest.make(_naming_test_impl)
+t1_test = unittest.make(_repository_bzl_test_impl)
+t2_test = unittest.make(_aliases_test_impl)
+
+def translate_package_lock_tests(name):
+    unittest.suite(name, t0_test, t1_test, t2_test)

test/BUILD.bazel

@@ -152,7 +152,7 @@ diff_test(
 
 nodejs_test(
     name = "test_test",
-    data = ["@npm__types_node-15.14.9"],
+    data = ["@npm_deps//@types/node"],
     entry_point = "test.js",
 )
 
@@ -206,7 +206,7 @@ write_file(
 
 nodejs_binary(
     name = "bin7",
-    data = ["@npm__gregmagolan_test-b-0.0.2"],
+    data = ["@npm_deps//@gregmagolan/test-b"],
     entry_point = "case7.js",
 )