Correct filenames for non-js compiled files, add test

.babelrc

@@ -0,0 +1,22 @@
+{
+  "presets": [
+    [
+      "@babel/preset-env",
+      {
+        "useBuiltIns": "usage",
+        "corejs": {
+          "version": 3
+        },
+        "targets": "last 2 versions"
+      }
+    ]
+  ],
+  "plugins": [
+    [
+      "@babel/plugin-transform-typescript",
+      {
+        "allowNamespaces": true
+      }
+    ]
+  ]
+}

karma.conf.js

@@ -22,14 +22,16 @@ module.exports = function(config) {
     files: [
       { pattern: "test/t1.js", watched: false },
       { pattern: "test/t2.js", watched: false },
-      { pattern: "test/t3.js", watched: false }
+      { pattern: "test/t3.js", watched: false },
+      { pattern: "test/t4.ts", watched: false }
     ],
     exclude: [],
 
     preprocessors: {
       "test/t1.js": ["rollup"],
       "test/t2.js": ["rollup"],
-      "test/t3.js": ["rollupNode"]
+      "test/t3.js": ["rollupNode"],
+      "test/t4.ts": ["rollupNodeTypescript"]
     },
 
     rollupPreprocessor: {
@@ -51,6 +53,24 @@ module.exports = function(config) {
             require("rollup-plugin-buble")()
           ]
         }
+      },
+      rollupNodeTypescript: {
+        base: "rollup",
+        options: {
+          plugins: [
+            require("rollup-plugin-node-resolve")({
+              extensions: [".js", ".ts"]
+            }),
+            require("rollup-plugin-commonjs")({
+              include: "node_modules/**",
+              extensions: [".js", ".ts"]
+            }),
+            require("rollup-plugin-babel")({
+              exclude: "node_modules/**",
+              extensions: [".js", ".ts"]
+            })
+          ]
+        }
       }
     }
   });

lib/index.js

@@ -43,6 +43,13 @@ function createPreprocessor(preconfig, config, emitter, logger) {
           const { sourcemap } = options.output;
 
           file.sourceMap = map;
+
+          /**
+           * for processors that have alternate source file extensions,
+           * make sure to use the output rollup file name
+           */
+          const parsedPath = path.parse(file.path);
+          file.path = `${parsedPath.dir}/${result.fileName}`;
 
           const processed =
             sourcemap === "inline"