fetch_test.go

func TestConfiguration_FetchData(t *testing.T) {
	errFromFetcher := errors.New("mock error")
	type fields struct {
		baseURL     string
		apiVersion  int
		fetcherFunc func(string) (io.ReadCloser, error)
	}
	tests := []struct {
		name               string
		fields             fields
		want               Person
		wantCallsToFetcher int
		wantErr            error
	}{
		{
			name: "errors when invalid api version",
			fields: fields{
				baseURL:    "",
				apiVersion: 3,
				fetcherFunc: func(string) (io.ReadCloser, error) {
					return nil, nil
				},
			},
			want:               Person{},
			wantCallsToFetcher: 0,
			wantErr:            ErrInvalidAPIVersion,
		},
		{
			name: "errors when fetcher returns error",
			fields: fields{
				baseURL:    "",
				apiVersion: 1,
				fetcherFunc: func(string) (io.ReadCloser, error) {
					return ioutil.NopCloser(bytes.NewBufferString("")), errFromFetcher
				},
			},
			want:               Person{},
			wantCallsToFetcher: 1,
			wantErr:            errFromFetcher,
		},
		{
			name: "decodes and maps from v1 response",
			fields: fields{
				baseURL:    "",
				apiVersion: 1,
				fetcherFunc: func(string) (io.ReadCloser, error) {
					return ioutil.NopCloser(bytes.NewBufferString(`
{"user_name":"test_user",
"dob":"1999-05-23T18:25:43.511Z",
"fav_sports":[{"name":"football","order":2},{"name":"hockey", "order":1}]}
					`)), nil
				},
			},
			want: Person{
				Name:   "test_user",
				Age:    21,
				Sports: []string{"hockey", "football"},
			},
			wantCallsToFetcher: 1,
			wantErr:            nil,
		},
		{
			name: "decodes and maps from v2 response",
			fields: fields{
				baseURL:    "",
				apiVersion: 2,
				fetcherFunc: func(string) (io.ReadCloser, error) {
					return ioutil.NopCloser(bytes.NewBufferString(`
{"name":"test_user",
"age":21,
"sports":["football","hockey"]}
					`)), nil
				},
			},
			want: Person{
				Name:   "test_user",
				Age:    21,
				Sports: []string{"football", "hockey"},
			},
			wantCallsToFetcher: 1,
			wantErr:            nil,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			mf := &mockFetcher{tt.fields.fetcherFunc, 0}
			c := Configuration{
				baseURL:    tt.fields.baseURL,
				apiVersion: tt.fields.apiVersion,
				fetcher:    mf,
			}
			got, err := c.FetchData()
			if tt.wantErr != nil {
				assert.Error(t, tt.wantErr, err)
			} else {
				assert.Nil(t, err)
			}
			assert.Equal(t, tt.want, got)
			assert.Equal(t, tt.wantCallsToFetcher, mf.calls)
		})
	}
}

type mockFetcher struct {
	fetchFunc func(url string) (io.ReadCloser, error)
	calls     int
}

func (m *mockFetcher) fetch(url string) (io.ReadCloser, error) {
	m.calls++
	return m.fetchFunc(url)
}