add tests for readAsArrayBuffer method #27

tests/unit/fileUtils.spec.js

@@ -87,4 +87,24 @@ describe('fileUtils.js', () => {
     fu.readFile('./foo.bar')
     expect(window.fetch.calledOnceWith('./foo.bar')).to.equal(true)
   })
+
+  it('readAsArrayBuffer resolves', async () => {
+    const blob = new Blob(['foo'])
+    const buffer = await fu.readAsArrayBuffer(blob)
+
+    const uint8Array = new Uint8Array(buffer)
+    const text = new TextDecoder().decode(uint8Array)    
+    expect(text).to.equal('foo')
+  })
+
+  it('readAsArrayBuffer rejects', async () => {
+    const r = new FileReader()
+    r.readAsArrayBuffer = () => {
+      r.dispatchEvent(new Event('error'), )
+    }
+    sinon.stub(window, 'FileReader').returns(r)
+  
+    const blob = new Blob(['foo'])
+    await expect(fu.readAsArrayBuffer(blob)).to.be.rejectedWith('Problem parsing input file.')
+  })
 })