fix: External map references (#457)

* fix: replace placeholders in assetFileNames

So that external source map references point to the right file. Gotta pass a real file to postcss or it does some funny things.

Fixes #455

packages/rollup/rollup.js

@@ -16,9 +16,15 @@ const emptyMappings = {
  mappings : "",
 };
 
-function extensionless(file) {
- return path.join(path.dirname(file), path.basename(file, path.extname(file)));
-}
+const makeFile = (details) => {
+ const { entry } = details;
+ const name = path.basename(entry, path.extname(entry));
+
+ return Object.assign(details, {
+ base : path.join(path.dirname(entry), name),
+ name,
+ });
+};
 
 module.exports = function(opts) {
  const options = Object.assign(Object.create(null), {
@@ -161,12 +167,10 @@ module.exports = function(opts) {
 
  // First pass is used to calculate JS usage of CSS dependencies
  Object.keys(bundles).forEach((entry) => {
- const file = {
+ const file = makeFile({
  entry,
-
- base : extensionless(entry),
- css : [],
- };
+ css : [],
+ });
 
  // Get CSS files being used by each entry point
  const css = Object.keys(bundles[entry].modules).filter(filter);
@@ -221,22 +225,24 @@ module.exports = function(opts) {
 
  // Common chunk only emitted if necessary
  if(common.size) {
- files.push({
+ files.push(makeFile({
  entry : options.common,
- base : extensionless(options.common),
  css : [ ...common.keys() ],
- });
+ }));
  }
  }
 
  await Promise.all(
  files
  .filter(({ css }) => css.length)
- .map(async ({ base, css }) => {
+ .map(async (details) => {
+ const { base, name, css } = details;
  const id = this.emitAsset(`${base}.css`);
 
  const result = await processor.output({
- to,
+ to : to.replace(/\[(name|extname)\]/g, (match, field) =>
+ (field === "name" ? name : ".css")
+ ),
  files : css,
  });
 

packages/rollup/test/__snapshots__/rollup.test.js.snap

@@ -163,6 +163,15 @@ Object {
 }
 `;
 
+exports[`/rollup.js should generate external source maps 2`] = `
+"/* packages/rollup/test/specimens/simple.css */
+.fooga {
+ color: red;
+}
+
+/*# sourceMappingURL=simple.css.map */"
+`;
+
 exports[`/rollup.js should handle assetFileNames being undefined 1`] = `
 "/* packages/rollup/test/specimens/simple.css */
 .fooga {

packages/rollup/test/rollup.test.js

@@ -240,6 +240,8 @@ describe("/rollup.js", () => {
  expect(JSON.parse(read("./rollup/external-source-maps/assets/simple.css.map"))).toMatchSnapshot({
  file : expect.any(String),
  });
+
+ expect(read("./rollup/external-source-maps/assets/simple.css")).toMatchSnapshot();
  });
 
  it("should warn & not export individual keys when they are not valid identifiers", async () => {