feat(extracttriggers): function name param to allow multi-trigger files

The extractTrigger function is now passed an additional param that indicates the current function
name (if not deploying). In conjunction with customising funcNameFromRelPath, this could be used to
allow a setup where more than one trigger per file is stored. This isn't the best for performance
but we have decided to allow the flexibility.

feat #6

Author: george43g

src/export-functions.ts

@@ -90,10 +90,13 @@ export interface ExportFunctionsConfig {
    * the behaviour of es6 modules using `export default`. You may customise this behaviour.
    * @param inputModule This object is the required CommonJS module that will be passed
    * as the only argument to this function.
+   * @param currentFunctionName this is only present if run during a function invocation
+   * rather than during deployment. It is useful if customising BFF to find more than
+   * one trigger per file.
    * @returns must return the actual function trigger to be exported to firebase functions.
    * @example exportFunctions({extractTrigger: (obj) => obj['default']})
    */
-  extractTrigger?: (inputModule: any) => any;
+  extractTrigger?: (inputModule: any, currentFunctionName?: string) => any;
 
   /**
    * Boolean value - wether to enable logging performance metrics
@@ -199,7 +202,7 @@ export function exportFunctions({
       try {
         // eslint-disable-next-line no-eval
         const mod = eval('require')(absPath); // This is to preserve require call in webpack
-        funcTrigger = extractTrigger(mod);
+        funcTrigger = extractTrigger(mod, getFunctionInstance());
       } catch (err) {
         console.error(err);
         continue;