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dig_test.go
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dig_test.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package dig
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestEndToEndSuccess(t *testing.T) {
t.Parallel()
t.Run("pointer", func(t *testing.T) {
c := New()
b := &bytes.Buffer{}
require.NoError(t, c.Provide(b), "provide failed")
require.NoError(t, c.Invoke(func(got *bytes.Buffer) {
require.NotNil(t, got, "invoke got nil buffer")
require.True(t, got == b, "invoke got wrong buffer")
}), "invoke failed")
})
t.Run("nil pointer", func(t *testing.T) {
// Dig shouldn't forbid this - it's perfectly reasonable to explicitly
// provide a typed nil, since that's often a convenient way to supply a
// default no-op implementation.
c := New()
require.NoError(t, c.Provide((*bytes.Buffer)(nil)), "provide failed")
require.NoError(t, c.Invoke(func(b *bytes.Buffer) {
require.Nil(t, b, "expected to get nil buffer")
}), "invoke failed")
})
t.Run("pointer constructor", func(t *testing.T) {
c := New()
var b *bytes.Buffer
require.NoError(t, c.Provide(func() *bytes.Buffer {
b = &bytes.Buffer{}
return b
}), "provide failed")
require.NoError(t, c.Invoke(func(got *bytes.Buffer) {
require.NotNil(t, got, "invoke got nil buffer")
require.True(t, got == b, "invoke got wrong buffer")
}), "invoke failed")
})
t.Run("struct", func(t *testing.T) {
c := New()
var buf bytes.Buffer
buf.WriteString("foo")
require.NoError(t, c.Provide(buf), "provide failed")
require.NoError(t, c.Invoke(func(b bytes.Buffer) {
// ensure we're getting back the buffer we put in
require.Equal(t, "foo", buf.String(), "invoke got new buffer")
}), "invoke failed")
})
t.Run("struct constructor", func(t *testing.T) {
c := New()
var buf bytes.Buffer
buf.WriteString("foo")
require.NoError(t, c.Provide(buf), "provide failed")
require.NoError(t, c.Invoke(func(b bytes.Buffer) {
// ensure we're getting back the buffer we put in
require.Equal(t, "foo", buf.String(), "invoke got new buffer")
}), "invoke failed")
})
t.Run("slice", func(t *testing.T) {
c := New()
b1 := &bytes.Buffer{}
b2 := &bytes.Buffer{}
bufs := []*bytes.Buffer{b1, b2}
require.NoError(t, c.Provide(bufs), "provide failed")
require.NoError(t, c.Invoke(func(bs []*bytes.Buffer) {
require.Equal(t, 2, len(bs), "invoke got unexpected number of buffers")
require.True(t, b1 == bs[0], "first item did not match")
require.True(t, b2 == bs[1], "second item did not match")
}), "invoke failed")
})
t.Run("slice constructor", func(t *testing.T) {
c := New()
b1 := &bytes.Buffer{}
b2 := &bytes.Buffer{}
require.NoError(t, c.Provide(func() []*bytes.Buffer {
return []*bytes.Buffer{b1, b2}
}), "provide failed")
require.NoError(t, c.Invoke(func(bs []*bytes.Buffer) {
require.Equal(t, 2, len(bs), "invoke got unexpected number of buffers")
require.True(t, b1 == bs[0], "first item did not match")
require.True(t, b2 == bs[1], "second item did not match")
}), "invoke failed")
})
t.Run("array", func(t *testing.T) {
c := New()
bufs := [1]*bytes.Buffer{{}}
require.NoError(t, c.Provide(bufs), "provide failed")
require.NoError(t, c.Invoke(func(bs [1]*bytes.Buffer) {
require.NotNil(t, bs[0], "invoke got new array")
}), "invoke failed")
})
t.Run("array constructor", func(t *testing.T) {
c := New()
bufs := [1]*bytes.Buffer{{}}
require.NoError(t, c.Provide(bufs), "provide failed")
require.NoError(t, c.Invoke(func(bs [1]*bytes.Buffer) {
require.NotNil(t, bs[0], "invoke got new array")
}), "invoke failed")
})
t.Run("map", func(t *testing.T) {
c := New()
m := map[string]string{}
require.NoError(t, c.Provide(m), "provide failed")
require.NoError(t, c.Invoke(func(m map[string]string) {
require.NotNil(t, m, "invoke got zero value map")
}), "invoke failed")
})
t.Run("map constructor", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() map[string]string {
return map[string]string{}
}), "provide failed")
require.NoError(t, c.Invoke(func(m map[string]string) {
require.NotNil(t, m, "invoke got zero value map")
}), "invoke failed")
})
t.Run("channel", func(t *testing.T) {
c := New()
ch := make(chan int)
require.NoError(t, c.Provide(ch), "provide failed")
require.NoError(t, c.Invoke(func(ch chan int) {
require.NotNil(t, ch, "invoke got nil chan")
}), "invoke failed")
})
t.Run("channel constructor", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() chan int {
return make(chan int)
}), "provide failed")
require.NoError(t, c.Invoke(func(ch chan int) {
require.NotNil(t, ch, "invoke got nil chan")
}), "invoke failed")
})
t.Run("func constructor", func(t *testing.T) {
// Functions passed directly to Provide are treated as constructors,
// but we can still put functions into the container with constructors.
// This makes injecting builders simple.
c := New()
require.NoError(t, c.Provide(func() func(int) {
return func(int) {}
}), "provide failed")
require.NoError(t, c.Invoke(func(f func(int)) {
require.NotNil(t, f, "invoke got nil function pointer")
}), "invoke failed")
})
t.Run("interface", func(t *testing.T) {
// TODO: This doesn't work as a reasonable user would expect, since
// passing an io.Writer as interface{} erases information. (Put
// differently, we go from having an io.Writer satisfied by a
// *bytes.Buffer to having an interface{} satisfied by *bytes.Buffer;
// the fact that the io.Writer interface was involved is lost forever.)
c := New()
var w io.Writer = &bytes.Buffer{}
require.NoError(t, c.Provide(w), "provide failed")
require.Error(t, c.Invoke(func(w io.Writer) {
}), "expected relying on provided interface to fail")
require.NoError(t, c.Invoke(func(b *bytes.Buffer) {
assert.NotNil(t, b, "expected to get concrete type of interface")
}), "expected relying on concrete type to succeed")
})
t.Run("interface constructor", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() io.Writer {
return &bytes.Buffer{}
}), "provide failed")
require.NoError(t, c.Invoke(func(w io.Writer) {
require.NotNil(t, w, "invoke got nil interface")
}), "invoke failed")
})
t.Run("param", func(t *testing.T) {
c := New()
type contents string
type Args struct {
Param
privateContents contents
Contents contents
}
require.NoError(t,
c.Provide(func(args Args) *bytes.Buffer {
// testify's Empty doesn't work on string aliases for some
// reason
require.Len(t, args.privateContents, 0, "private contents must be empty")
require.NotEmpty(t, args.Contents, "contents must not be empty")
return bytes.NewBufferString(string(args.Contents))
}), "provide constructor failed")
require.NoError(t,
c.Provide(contents("hello world")),
"provide value failed")
require.NoError(t, c.Invoke(func(buff *bytes.Buffer) {
out, err := ioutil.ReadAll(buff)
require.NoError(t, err, "read from buffer failed")
require.Equal(t, "hello world", string(out), "contents don't match")
}))
})
t.Run("param pointer", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() io.Writer {
return new(bytes.Buffer)
}), "provide failed")
type Args struct {
Param
Writer io.Writer
}
require.NoError(t, c.Invoke(func(args *Args) {
require.NotNil(t, args, "args must not be nil")
require.NotNil(t, args.Writer, "writer must not be nil")
}), "invoke failed")
})
t.Run("invoke param", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() *bytes.Buffer {
return new(bytes.Buffer)
}), "provide failed")
type Args struct {
Param
privateBuffer *bytes.Buffer
*bytes.Buffer
}
require.NoError(t, c.Invoke(func(args Args) {
require.Nil(t, args.privateBuffer, "private buffer must be nil")
require.NotNil(t, args.Buffer, "invoke got nil buffer")
}))
})
t.Run("multiple-type constructor", func(t *testing.T) {
c := New()
constructor := func() (*bytes.Buffer, []int, error) {
return &bytes.Buffer{}, []int{42}, nil
}
consumer := func(b *bytes.Buffer, nums []int) {
assert.NotNil(t, b, "invoke got nil buffer")
assert.Equal(t, 1, len(nums), "invoke got empty slice")
}
require.NoError(t, c.Provide(constructor), "provide failed")
require.NoError(t, c.Invoke(consumer), "invoke failed")
})
t.Run("multiple-type constructor is called once", func(t *testing.T) {
c := New()
type A struct{}
type B struct{}
count := 0
constructor := func() (*A, *B, error) {
count++
return &A{}, &B{}, nil
}
getA := func(a *A) {
assert.NotNil(t, a, "got nil A")
}
getB := func(b *B) {
assert.NotNil(t, b, "got nil B")
}
require.NoError(t, c.Provide(constructor), "provide failed")
require.NoError(t, c.Invoke(getA), "A invoke failed")
require.NoError(t, c.Invoke(getB), "B invoke failed")
require.NoError(t, c.Invoke(func(a *A, b *B) {}), "AB invoke failed")
require.Equal(t, 1, count, "Constructor must be called once")
})
t.Run("method invocation inside Invoke", func(t *testing.T) {
c := New()
type A struct{}
type B struct{}
cA := func() (*A, error) {
return &A{}, nil
}
cB := func() (*B, error) {
return &B{}, nil
}
getA := func(a *A) {
c.Invoke(func(b *B) {
assert.NotNil(t, b, "got nil B")
})
assert.NotNil(t, a, "got nil A")
}
require.NoError(t, c.Provide(cA), "provide failed")
require.NoError(t, c.Provide(cB), "provide failed")
require.NoError(t, c.Invoke(getA), "A invoke failed")
})
t.Run("collections and instances of same type", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() []*bytes.Buffer {
return []*bytes.Buffer{{}}
}), "providing collection failed")
require.NoError(t, c.Provide(func() *bytes.Buffer {
return &bytes.Buffer{}
}), "providing pointer failed")
})
}
func TestProvideConstructorErrors(t *testing.T) {
t.Run("multiple-type constructor returns multiple objects of same type", func(t *testing.T) {
c := New()
type A struct{}
constructor := func() (*A, *A, error) {
return &A{}, &A{}, nil
}
require.Error(t, c.Provide(constructor), "provide failed")
})
}
func TestParamsDontRecurse(t *testing.T) {
t.Parallel()
t.Run("param field", func(t *testing.T) {
type anotherParam struct {
Param
Reader io.Reader
}
type someParam struct {
Param
Writer io.Writer
Another anotherParam
}
c := New()
err := c.Provide(func(a someParam) *bytes.Buffer {
panic("constructor must not be called")
})
require.Error(t, err, "provide must fail")
require.Contains(t, err.Error(),
"parameter objects may not be used as fields of other parameter objects")
require.Contains(t, err.Error(),
"field Another (type dig.anotherParam) of dig.someParam is a parameter object")
})
}
func TestProvideRespectsConstructorErrors(t *testing.T) {
t.Run("constructor succeeds", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() (*bytes.Buffer, error) {
return &bytes.Buffer{}, nil
}), "provide failed")
require.NoError(t, c.Invoke(func(b *bytes.Buffer) {
require.NotNil(t, b, "invoke got nil buffer")
}), "invoke failed")
})
t.Run("constructor fails", func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(func() (*bytes.Buffer, error) {
return nil, errors.New("oh no")
}), "provide failed")
var called bool
err := c.Invoke(func(b *bytes.Buffer) { called = true })
assert.Contains(t, err.Error(), "oh no", "expected to bubble up constructor error")
assert.False(t, called, "shouldn't call invoked function when deps aren't available")
})
}
func TestCantProvideUntypedNil(t *testing.T) {
t.Parallel()
c := New()
assert.Error(t, c.Provide(nil))
}
func TestCantProvideErrors(t *testing.T) {
t.Parallel()
c := New()
assert.Error(t, c.Provide(func() error { return errors.New("foo") }))
// TODO: This is another case where we're losing type information, which
// (again) makes the provide-instance path behave differently from the
// provide-constructor path. This is fixable by not allowing users to
// provide types that *implement* error, but let's discuss a holistic
// solution.
assert.NoError(t, c.Provide(errors.New("foo")))
}
type someError struct{}
var _ error = (*someError)(nil)
func (*someError) Error() string { return "foo" }
func TestCanProvideErrorLikeType(t *testing.T) {
t.Parallel()
tests := []interface{}{
func() *someError { return &someError{} },
func() (*someError, error) { return &someError{}, nil },
&someError{},
}
for _, tt := range tests {
t.Run(fmt.Sprintf("%T", tt), func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(tt), "provide must not fail")
require.NoError(t, c.Invoke(
func(err *someError) {
assert.NotNil(t, err, "invoke received nil")
}), "invoke must not fail")
})
}
}
func TestCantProvideParameterObjects(t *testing.T) {
t.Parallel()
t.Run("instance", func(t *testing.T) {
type Args struct{ Param }
c := New()
err := c.Provide(Args{})
require.Error(t, err, "provide should fail")
require.Contains(t, err.Error(), "can't provide parameter objects")
})
t.Run("pointer", func(t *testing.T) {
type Args struct{ Param }
c := New()
err := c.Provide(&Args{})
require.Error(t, err, "provide should fail")
require.Contains(t, err.Error(), "can't provide parameter objects")
})
t.Run("constructor", func(t *testing.T) {
type Args struct{ Param }
c := New()
err := c.Provide(func() (Args, error) {
panic("great sadness")
})
require.Error(t, err, "provide should fail")
require.Contains(t, err.Error(), "can't provide parameter objects")
})
t.Run("constructor pointer", func(t *testing.T) {
type Args struct{ Param }
c := New()
err := c.Provide(func() (*Args, error) {
panic("great sadness")
})
require.Error(t, err, "provide should fail")
require.Contains(t, err.Error(), "can't provide parameter objects")
})
}
func TestProvideKnownTypesFails(t *testing.T) {
t.Parallel()
provideArgs := []interface{}{
func() *bytes.Buffer { return nil },
func() (*bytes.Buffer, error) { return nil, nil },
&bytes.Buffer{},
}
for _, first := range provideArgs {
t.Run(fmt.Sprintf("%T", first), func(t *testing.T) {
c := New()
require.NoError(t, c.Provide(first), "first provide must not fail")
for _, second := range provideArgs {
assert.Error(t, c.Provide(second), "second provide must fail")
}
})
}
t.Run("provide constructor twice", func(t *testing.T) {
c := New()
assert.NoError(t, c.Provide(func() *bytes.Buffer { return nil }))
assert.Error(t, c.Provide(func() *bytes.Buffer { return nil }))
})
t.Run("provide instance and constructor fails", func(t *testing.T) {
c := New()
assert.NoError(t, c.Provide(&bytes.Buffer{}))
assert.Error(t, c.Provide(func() *bytes.Buffer { return nil }))
})
t.Run("provide constructor then object instance fails", func(t *testing.T) {
c := New()
assert.NoError(t, c.Provide(func() *bytes.Buffer { return nil }))
assert.Error(t, c.Provide(&bytes.Buffer{}))
})
}
func TestProvideCycleFails(t *testing.T) {
t.Parallel()
// A <- B <- C
// | ^
// |_________|
type A struct{}
type B struct{}
type C struct{}
newA := func(*C) *A { return &A{} }
newB := func(*A) *B { return &B{} }
newC := func(*B) *C { return &C{} }
c := New()
assert.NoError(t, c.Provide(newA))
assert.NoError(t, c.Provide(newB))
err := c.Provide(newC)
require.Error(t, err, "expected error when introducing cycle")
require.Contains(t, err.Error(), "cycle")
}
func TestIncompleteGraphIsOkay(t *testing.T) {
t.Parallel()
// A <- B <- C
// Even if we don't provide B, we should be able to resolve A.
type A struct{}
type B struct{}
type C struct{}
newA := func() *A { return &A{} }
newC := func(*B) *C { return &C{} }
c := New()
assert.NoError(t, c.Provide(newA), "provide failed")
assert.NoError(t, c.Provide(newC), "provide failed")
assert.NoError(t, c.Invoke(func(*A) {}), "invoke failed")
}
func TestProvideFuncsWithoutReturnsFails(t *testing.T) {
t.Parallel()
c := New()
assert.Error(t, c.Provide(func(*bytes.Buffer) {}))
}
func TestInvokesUseCachedObjects(t *testing.T) {
t.Parallel()
c := New()
constructorCalls := 0
buf := &bytes.Buffer{}
require.NoError(t, c.Provide(func() *bytes.Buffer {
assert.Equal(t, 0, constructorCalls, "constructor must not have been called before")
constructorCalls++
return buf
}))
calls := 0
for i := 0; i < 3; i++ {
assert.NoError(t, c.Invoke(func(b *bytes.Buffer) {
calls++
require.Equal(t, 1, constructorCalls, "constructor must be called exactly once")
require.Equal(t, buf, b, "invoke got different buffer pointer")
}), "invoke %d failed", i)
require.Equal(t, i+1, calls, "invoked function not called")
}
}
func TestInvokeFailures(t *testing.T) {
t.Parallel()
t.Run("untyped nil", func(t *testing.T) {
c := New()
assert.Error(t, c.Invoke(nil))
})
t.Run("unmet dependency", func(t *testing.T) {
c := New()
assert.Error(t, c.Invoke(func(*bytes.Buffer) {}))
})
t.Run("returned error", func(t *testing.T) {
c := New()
assert.Error(t, c.Invoke(func() error { return errors.New("oh no") }))
})
t.Run("many returns", func(t *testing.T) {
c := New()
assert.Error(t, c.Invoke(func() (int, error) { return 42, errors.New("oh no") }))
})
}