fix: adding new files w/ rollup shouldn't error

.travis.yml

@@ -20,14 +20,14 @@ cache:
   directories:
   - "$HOME/.npm"
 
-# Set up latest npm & cipm for installs
+# Set up npm 5 for installs (npm 6 seems busted atm)
 before_install:
  - npm config set loglevel warn
- - npm install --global npm@latest cipm
+ - npm install --global npm@5
 
 install:
-- cipm
-- lerna exec -- cipm
+- npm ci
+- lerna exec -- npm ci
 
 script:
 - npm test -- --coverage --verbose --ci

packages/core/processor.js

@@ -169,7 +169,7 @@ Processor.prototype = {
             .filter((file) => this._graph.hasNode(file));
 
         if(!files.length) {
-            return;
+            return [];
         }
 
         // Remove everything that depends on files to be removed as well

packages/rollup/rollup.js

@@ -44,7 +44,7 @@ module.exports = function(opts) {
         },
 
         transform : function(code, id) {
-            let removed;
+            let removed = [];
 
             if(!filter(id) || id.slice(slice) !== options.ext) {
                 return null;
@@ -54,8 +54,6 @@ module.exports = function(opts) {
             // avoid cache staleness issues
             if(runs) {
                 removed = processor.remove(id);
-            } else {
-                removed = [];
             }
 
             return Promise.all(

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

@@ -101,6 +101,15 @@ console.log(css);
 }
 `;
 
+exports[`/rollup.js watch should correctly add new css files in watch mode when files change 1`] = `""`;
+
+exports[`/rollup.js watch should correctly add new css files in watch mode when files change 2`] = `
+"/* packages/rollup/test/output/one.css */
+.mc19ef5610_one {
+    color: red;
+}"
+`;
+
 exports[`/rollup.js watch should correctly update files within the dependency graph in watch mode when files change 1`] = `
 "/* packages/rollup/test/output/one.css */
 .mc19ef5610_one {

packages/rollup/test/rollup.test.js

@@ -422,5 +422,62 @@ describe("/rollup.js", () => {
                 return done();
             }));
         });
+
+        it("should correctly add new css files in watch mode when files change", (done) => {
+            // Create v1 of the files
+            fs.writeFileSync(
+                "./packages/rollup/test/output/one.css",
+                dedent(`
+                    .one {
+                        color: red;
+                    }
+                `)
+            );
+
+            fs.writeFileSync(
+                "./packages/rollup/test/output/watch.js",
+                dedent(`
+                    console.log("hello");
+                `)
+            );
+
+            // Start watching (re-requiring rollup because it needs root obj reference)
+            watcher = watch({
+                input  : require.resolve("./output/watch.js"),
+                output : {
+                    file   : "./packages/rollup/test/output/watch-output.js",
+                    format : "es"
+                },
+                plugins : [
+                    plugin({
+                        css : "./packages/rollup/test/output/watch-output.css",
+                        map : false
+                    })
+                ]
+            });
+
+            // Create v2 of the file after a bit
+            setTimeout(() => fs.writeFileSync(
+                "./packages/rollup/test/output/watch.js",
+                dedent(`
+                    import css from "./one.css";
+
+                    console.log(css);
+                `)
+            ), 200);
+
+            watcher.on("event", watching((builds) => {
+                if(builds === 1) {
+                    expect(read("watch-output.css")).toMatchSnapshot();
+
+                    // continue watching
+                    return;
+                }
+
+                expect(read("watch-output.css")).toMatchSnapshot();
+
+                return done();
+            }));
+        });
     });
 });