Idiomatic Golang Tests

Transcript

1. IDIOMATIC GOLANG TESTS
   A GUIDE TO
   

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2. WHY TO TEST?
   

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3. TO DOCUMENT
   

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4. TO ENSURE IT WORKS
   

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5. TO WRITE BETTER CODE
   

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6. HOW TO TEST?
   

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7. package simple_calculator
   func Sum(a int, b int) int {
   return a + b
   }
   

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8. func TestSumValid(t *testing.T) {
   got := Sum(2, 2)
   if got != 4 {
   t.Errorf("Sum() = %v, want %v", got, 4)
   }
   }
   func TestSumInvalid(t *testing.T) {
   // some test logic here
   }
   

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9. $ go test -v ./
   === RUN TestSumValid
   --- PASS: TestSumValid (0.00s)
   === RUN TestSumInvalid
   --- PASS: TestSumInvalid (0.00s)
   PASS
   ok simple_calculator 0.008s
   

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10. SUB TESTS
    

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11. func TestSum(t *testing.T) {
    t.Run("sum-valid", func(t *testing.T) {
    got := Sum(2, 2)
    if got != 4 {
    t.Errorf("Sum() = %v, want %v", got, 4)
    }
    })
    t.Run("sum-invalid", func(t *testing.T) {
    // some test logic here
    })
    }
    

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12. $ go test -v ./
    === RUN TestSum
    === RUN TestSum/sum-valid
    === RUN TestSum/sum-invalid
    --- PASS: TestSum (0.00s)
    --- PASS: TestSum/sum-valid (0.00s)
    --- PASS: TestSum/sum-invalid (0.00s)
    ok simple_calculator 0.008s
    

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13. TABLE DRIVEN
    

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14. type args struct {
    a int
    b int
    }
    type testCase struct {
    name string
    args args
    want int
    }
    tests := []testCase{
    {"sum 2+2", args{1, 2}, 3},
    }
    

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15. for _, tt := range tests {
    t.Run(tt.name, func(t *testing.T) {
    got := Sum(tt.args.a, tt.args.b)
    if got != tt.want {
    t.Errorf("Sum() = %v, want %v", got, tt.want)
    }
    })
    }
    

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16. $ go test -v ./
    === RUN TestSum
    === RUN TestSum/sum_2+2
    --- PASS: TestSum (0.00s)
    --- PASS: TestSum/sum_2+2 (0.00s)
    ok simple_calculator 0.008s
    

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17. TEXT
    TABLE DRIVEN TESTS
    ▸ Easy to add new test cases
    ▸ Don’t repeat same logic
    ▸ Easy to reproduce bugs
    ▸ Can be used even for one test case
    

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18. func Fibonacci(n uint) uint {
    if n <= 1 {
    return n
    }
    var n2, n1 = uint(0), uint(1)
    for i := uint(1); i < n; i++ {
    n2 = n2 + n1
    n1, n2 = n2, n1
    }
    return n1
    }
    

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19. func TestFibonacci(t *testing.T) {
    tests := []struct {
    name string
    number uint
    want uint
    }{
    {"10", 10, 55},
    {"50", 50, 12586269025},
    {"9999999999", 9999999999, 2225628016866617058},
    }
    for _, tt := range tests {
    t.Run(tt.name, func(t *testing.T) {
    if got := Fibonacci(tt.number); got != tt.want {
    t.Errorf("Fibonacci() = %v, want %v", got, tt.want)
    }
    })
    }
    }
    

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20. $ go test -v ./
    === RUN TestFibonacci
    === RUN TestFibonacci/10
    === RUN TestFibonacci/50
    === RUN TestFibonacci/9999999999
    --- PASS: TestFibonacci (7.49s)
    --- PASS: TestFibonacci/10 (0.00s)
    --- PASS: TestFibonacci/50 (0.00s)
    --- PASS: TestFibonacci/9999999999 (7.49s)
    PASS
    ok simple_calculator 7.502s
    

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21. FLAGS
    

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22. var skipSlow = flag.Bool("skipSlow", false, "Skip slow tests")
    

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23. func TestFibonacci(t *testing.T) {
    tests := []struct {
    name string
    number uint
    want uint
    isSlow bool
    }{
    {"10", 10, 55, false},
    {"50", 50, 12586269025, false},
    {"9999999999", 9999999999, 2225628016866617058, true},
    }
    for _, tt := range tests {
    t.Run(tt.name, func(t *testing.T) {
    if *skipSlow && tt.isSlow {
    t.Skipf("Skiped slow test")
    }
    if got := Fibonacci(tt.number); got != tt.want {
    t.Errorf("Fibonacci() = %v, want %v", got, tt.want)
    }
    })
    }
    }
    

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24. $ go test -v -skipSlow ./
    === RUN TestFibonacci
    === RUN TestFibonacci/10
    === RUN TestFibonacci/50
    === RUN TestFibonacci/9999999999
    --- PASS: TestFibonacci (0.00s)
    --- PASS: TestFibonacci/10 (0.00s)
    --- PASS: TestFibonacci/50 (0.00s)
    --- SKIP: TestFibonacci/9999999999 (0.00s)
    calculator_test.go:73: Skiped slow test
    PASS
    ok simple_calculator 0.008s
    

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25. RACE CONDITIONS
    

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26. type Item struct {
    Value int
    }
    func (item Item) PersistRand(n int) {
    rand.Seed(time.Now().UnixNano())
    for i := 0; i < n; i++ {
    go func() {
    item.Value = rand.Int()
    }()
    }
    }
    

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27. $ go test -v ./
    === RUN TestItem_PersistRand
    === RUN TestItem_PersistRand/10
    --- PASS: TestItem_PersistRand (0.00s)
    --- PASS: TestItem_PersistRand/10 (0.00s)
    PASS
    ok idiomatic-tests-examples/kv 0.010s
    

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28. $ go test -v -race ./
    === RUN TestItem_PersistRand
    === RUN TestItem_PersistRand/10
    ==================
    WARNING: DATA RACE
    Write at 0x00c0000920c0 by goroutine 9:
    idiomatic-tests-examples/kv.Item.PersistRand.func1()
    /Users/hussani/projects/go-workspace/src/idiomatic-tests-
    examples/kv/storage.go:17 +0x46
    Previous write at 0x00c0000920c0 by goroutine 8:
    idiomatic-tests-examples/kv.Item.PersistRand.func1()
    

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29. FIXTURES
    

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30. func TestPersistRand(t *testing.T) {
    data := filepath.Join(
    "test-fixtures",
    "persist-data.json.fixture"
    )
    // Do something on test using data
    }
    

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31. TEXT
    FIXTURES
    ▸ Use to complex string input
    ▸ Use to iterate on system folders
    ▸ Use to loads configuration , json, binary data, etc
    

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32. GOLDEN FILES
    

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33. func TestFetchPersist(t *testing.T) {
    // a table test case
    for _, tc := range testCases {
    golden := filepath.Join(
    "test-fixtures",
    tc.name + ".golden"
    )
    expected, _ := ioutil.ReadFile(golden)
    if got := doSomething(tc.input); got != expected {
    t.Errorf("doSomething() result doesn't match golden. got %v", got)
    }
    )
    }
    

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34. TEXT
    GOLDEN FILES
    ▸ Use to compare complex string output
    ▸ Need to be updated always your output changes
    

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35. SUMMARY
    

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36. TEXT
    SUMMARY
    ▸ Always do tests! They are important
    ▸ Test using Table Driven
    ▸ Use flags to control some test execution
    ▸ Always execute tests with race flag
    ▸ Don’t put complex or long strings on your test file
    ▸ Use Fixtures & Golden files
    ▸ Happy testing :)
    

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37. THANKS!
    twitter.com/hussanii
    

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