allow file postprocessors

Author: reflector-six

src/dts-content.ts

@@ -68,13 +68,15 @@ export class DtsContent {
         return path.join(this.rootDir, this.searchDir, this.rInputPath);
     }
 
-    public async writeFile(): Promise<void> {
+    public async writeFile(postprocessor = (formatted: string) => formatted): Promise<void> {
+        const finalOutput = postprocessor(this.formatted);
+
         const outPathDir = path.dirname(this.outputFilePath);
         if(!isThere(outPathDir)) {
             mkdirp.sync(outPathDir);
         }
 
-        await writeFile(this.outputFilePath, this.formatted, 'utf8');
+        await writeFile(this.outputFilePath, finalOutput, 'utf8');
     }
 }
 

test/dts-creator.spec.ts

@@ -180,6 +180,19 @@ export = styles;
   });
 
   describe('#writeFile', () => {
+    it('accepts a postprocessor function', done => {
+      new DtsCreator()
+        .create('test/testStyle.css')
+        .then(content => {
+          return content.writeFile(
+            formatted => `// this banner was added to the .d.ts file automatically.\n${formatted}`
+          );
+        })
+        .then(() => {
+          done();
+        });
+    });
+
     it('writes a file', done => {
       new DtsCreator()
         .create('test/testStyle.css')