code: function _serveFile(requestedFile, done) {
        requestedFile.path = transformPath(requestedFile.path);
  
        log.debug(`Fetching ${requestedFile.path} from buffer`);
  
        // We get a requestedFile with an sha when Karma is watching files on
        // disk, and the file requested changed. When this happens, we need to
        // recompile the whole lot.
        if (requestedFile.sha) {
          delete requestedFile.sha; // Hack used to prevent infinite loop.
          enqueueForServing(requestedFile, done);
          // eslint-disable-next-line no-use-before-define
          compile();
          return;
        }
  
        const normalized = _normalize(requestedFile.path);
        const compiled = compilationResults[normalized];
        if (compiled) {
          delete compilationResults[normalized];
          done(null, compiled.contents.toString());
          return;
        }
  
        // If the file was not found in the stream, then maybe it is not compiled
        // or it is a definition file.
        log.debug(`${requestedFile.originalPath} was not found. Maybe it was \
  not compiled or it is a definition file.`);
        done(null, dummyFile("This file was not compiled"));
      }
docs: Used to fetch files from buffer.