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Context("simulate an error retrieving data from S3", func() {
        var testCall *gomock.Call
        BeforeEach(func() {
                testCall = mockFetcher.EXPECT().GetObject(gomock.Any()).Return(nil, fmt.Errorf("AWS error")).AnyTimes()
        })
        It("and fails", func() {
                _, err := ReadPersonFromS3(mockFetcher)
                Expect(err).To(HaveOccurred())
                testCall.Times(1)
        })

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Context("ReadPersonFromS3 -- using mock", func() {
        bucket := "testbucket"
        key := "persondata.txt"
        objectInput := &s3.GetObjectInput{
                Bucket: aws.String(bucket),
                Key:    aws.String(key),
        }
        goodObjectOutput := &s3.GetObjectOutput{
                Body: S3Fetcher.NewMockBody([]byte(goodJson)),
        }

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var _ = Describe("Person", func() {
        var (
                mockFetcher *mock_S3Fetcher.MockS3Fetcher
                ctrl    *gomock.Controller
        )
        BeforeEach(func() {
                ctrl = gomock.NewController(GinkgoT())
        })
        AfterEach(func() {
                ctrl.Finish()

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import (
    …
    "github.com/tapjoy/gomockblog/mocks/mock_s3fetcher"
    …
}

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var svc S3Fetcher.S3Fetcher
var err error
var jsonData string = goodJson

JustBeforeEach(func() {
        svc, err = S3Fetcher.NewStringFetcher(jsonData)
})

Context("ReadPersonFromS3", func() {
        It("successfully reads data from S3", func() {

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package person_test

import (
        . "github.com/tapjoy/mocks3fetcher/person"
        . "github.com/onsi/ginkgo"
        . "github.com/onsi/gomega"
)

var _ = Describe("person", func() {
        goodJson := `

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func downloadS3Data(fetcher S3Fetcher, bucket string, key string) ([]byte, error) {
       results, err := fetcher.GetObject(&s3.GetObjectInput{
                 Bucket: aws.String(bucket),
                 Key:    aws.String(key),
       })

       if err != nil {
                 return nil, err
       }
       defer results.Body.Close()

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type MockBody struct {
       buf *bytes.Buffer
}

func (m MockBody) Close() error {
       return nil
}

func (m MockBody) Read(p []byte) (n int, err error) {
       return m.buf.Read(p)

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func (fetcher *fileFetcher) GetObject(s3Input *s3.GetObjectInput) (*s3.GetObjectOutput, error) {
       // completely ignore the input, just return an object wrapping the fetcher.data
       log.Printf("reading offers from file '%s'", fetcher.file)

       return &s3.GetObjectOutput{
               Body: *(NewMockBody(fetcher.data)),
       }, nil
}

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type fileFetcher struct {
       data []byte
       file string
}

func NewFileFetcher(filename string) (S3Fetcher, error) {
       // read contents of file
       jsonBuff, err := ioutil.ReadFile(filename)
       if err != nil {
               return nil, err