Check that all V*.elm modules are exposed.

Makefile

@@ -6,6 +6,10 @@ SHELL:=env PATH=${PATH} /bin/sh
 test: elm-stuff tests/elm-stuff node_modules
 	elm-test
 
+.PHONY: checks
+checks:
+	scripts/check-exposed.py
+
 .PHONY: diff
 diff: node_modules elm-stuff
 	if (elm-package diff | tee /dev/stderr | grep -q MAJOR); then echo "MAJOR changes are not allowed!"; exit 1; fi
@@ -49,4 +53,4 @@ elm-stuff: elm-package.json node_modules
 setup: node_modules elm-stuff tests/elm-stuff styleguide-app/elm-stuff
 
 .PHONY: ci
-ci: test format documentation.json diff styleguide-app/elm.js
+ci: checks test format documentation.json diff styleguide-app/elm.js

scripts/check-exposed.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+#
+# Checks that `elm-package.json` contains an `exposed-modules` entry for every
+# module in `src/Nri` (recursively) named `Vn.elm`, where `n` is a decimal
+# number.
+#
+# On success, this emits nothing and exits 0.
+#
+# On failure, this emits a list of those modules not exposed, and exits 2.
+#
+
+import json
+import os
+import re
+import sys
+
+
+re_v_file = re.compile(r"^V[0-9]+[.]elm$")
+re_module = re.compile(
+    r"""
+    # Zero or more blank lines or single-line comments.
+      (?:^$\n|^--.*$\n)*
+    # Optional port or effect modifier.
+      ^(?:(?:port|effect)\s+)?
+    # The module declaration itself begins.
+      module
+    # Optional newline, comment, newline.
+      (?:\n\s+--.+\n)?
+    # After some whitespace, capture the module name.
+      \s+(?P<module>[^ ]+)\b
+    """,
+    flags=re.MULTILINE | re.VERBOSE)
+
+
+def p_v_file(filename):
+    """Is `filename` a versioned widget file?"""
+    return re_v_file.match(filename) is not None
+
+
+def read_module(filename):
+    """Read the module name from the Elm source."""
+    with open(filename, "r", encoding="utf-8") as elm:
+        return re_module.search(elm.read()).group("module")
+
+
+def find_v_modules():
+    for dirname, dirnames, filenames in os.walk("src/Nri"):
+        filenames = filter(p_v_file, filenames)
+        filepaths = (os.path.join(dirname, filename) for filename in filenames)
+        yield from map(read_module, filepaths)
+
+
+def read_exposed_modules():
+    with open("elm-package.json", "rb") as pkg:
+        yield from json.load(pkg).get("exposed-modules")
+
+
+if __name__ == "__main__":
+    available = set(find_v_modules())
+    exposed = set(read_exposed_modules())
+    missing = available - exposed
+    for module in sorted(missing):
+        print("Not exposed:", module, file=sys.stderr)
+    raise SystemExit(
+        0 if len(missing) == 0 else 2)