dig_test.go

// 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"
	"io"
	"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()
		require.NoError(t, c.Provide(&bytes.Buffer{}), "provide failed")
		require.NoError(t, c.Invoke(func(b *bytes.Buffer) {
			require.NotNil(t, b, "invoke got nil 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()
		require.NoError(t, c.Provide(func() *bytes.Buffer {
			return &bytes.Buffer{}
		}), "provide failed")
		require.NoError(t, c.Invoke(func(b *bytes.Buffer) {
			require.NotNil(t, b, "invoke got nil buffer")
		}), "invoke failed")
	})

	t.Run("struct", func(t *testing.T) {
		c := New()
		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()
		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()
		bufs := []*bytes.Buffer{{}, {}}
		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")
		}), "invoke failed")
	})

	t.Run("slice constructor", func(t *testing.T) {
		c := New()
		require.NoError(t, c.Provide(func() []*bytes.Buffer {
			return []*bytes.Buffer{{}, {}}
		}), "provide failed")
		require.NoError(t, c.Invoke(func(bs []*bytes.Buffer) {
			require.Equal(t, 2, len(bs), "invoke got unexpected number of buffers")
		}), "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("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("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 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")))
}

func TestProvideKnownTypesFails(t *testing.T) {
	t.Parallel()
	c := New()
	assert.NoError(t, c.Provide(func() *bytes.Buffer { return nil }))
	assert.Error(t, c.Provide(func() *bytes.Buffer { return nil }))
}

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()
	calls := 0
	buf := &bytes.Buffer{}
	require.NoError(t, c.Provide(func() *bytes.Buffer { return buf }))

	for i := 0; i < 3; i++ {
		assert.NoError(t, c.Invoke(func(b *bytes.Buffer) {
			calls++
			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") }))
	})
}