feat: Implement resource mapper for the file resource store (#142)

* move file mapping logic to resourcemapper

* make filestore dependent of resource mapper

* set default contenttype

* refactor fileresourcemapper

* fix map function

* refactor

* add normalized parser

* refactor unit test

* fix metadata problem

* refactor names

* reverse change

* add getters

* add comments

* add comments, move code

* change text/turtle to constant

* add changes

* add requested changes

* add more requested changes

* add more requested changes

* more changes

test/unit/storage/ExtensionBasedMapper.test.ts

@@ -0,0 +1,21 @@
+import { RuntimeConfig } from '../../../src/init/RuntimeConfig';
+import { ExtensionBasedMapper } from '../../../src/storage/ExtensionBasedMapper';
+
+describe('An ExtensionBasedMapper', (): void => {
+  const base = 'http://test.com/';
+  const rootFilepath = 'uploads/';
+  const resourceMapper = new ExtensionBasedMapper(new RuntimeConfig({ base, rootFilepath }));
+
+  it('returns the correct url of a file.', async(): Promise<void> => {
+    let result = resourceMapper.mapFilePathToUrl(`${rootFilepath}test.txt`);
+    expect(result).toEqual(`${base}test.txt`);
+
+    result = resourceMapper.mapFilePathToUrl(`${rootFilepath}image.jpg`);
+    expect(result).toEqual(`${base}image.jpg`);
+  });
+
+  it('errors when filepath does not contain rootFilepath.', async(): Promise<void> => {
+    expect((): string => resourceMapper.mapFilePathToUrl('random/test.txt')).toThrow(Error);
+    expect((): string => resourceMapper.mapFilePathToUrl('test.txt')).toThrow(Error);
+  });
+});