app_test.go

// Copyright (c) 2020 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 fx_test

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"testing"
	"time"

	. "go.uber.org/fx"
	"go.uber.org/fx/fxtest"
	"go.uber.org/fx/internal/fxlog"
	"go.uber.org/multierr"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func NewForTest(t testing.TB, opts ...Option) *App {
	testOpts := []Option{Logger(fxtest.NewTestPrinter(t))}
	opts = append(testOpts, opts...)
	return New(opts...)
}

func TestNewApp(t *testing.T) {
	t.Run("ProvidesLifecycleAndShutdowner", func(t *testing.T) {
		var (
			l Lifecycle
			s Shutdowner
		)
		fxtest.New(
			t,
			Populate(&l, &s),
		)
		assert.NotNil(t, l)
		assert.NotNil(t, s)
	})

	t.Run("OptionsHappensBeforeProvides", func(t *testing.T) {
		// Should be grouping all provides and pushing them into the container
		// after applying other options. This prevents the app configuration
		// (e.g., logging) from changing halfway through our provides.

		spy := new(fxlog.Spy)
		app := fxtest.New(t, Provide(func() struct{} { return struct{}{} }), Logger(spy))
		defer app.RequireStart().RequireStop()
		assert.Contains(t, spy.String(), "PROVIDE\tstruct {}")
	})

	t.Run("CircularGraphReturnsError", func(t *testing.T) {
		type A struct{}
		type B struct{}
		app := NewForTest(t,
			Provide(func(A) B { return B{} }),
			Provide(func(B) A { return A{} }),
			Invoke(func(B) {}),
		)
		err := app.Err()
		require.Error(t, err, "fx.New should return an error")

		errMsg := err.Error()
		assert.Contains(t, errMsg, "cycle detected in dependency graph")
		assert.Contains(t, errMsg, "depends on fx_test.A")
		assert.Contains(t, errMsg, "depends on fx_test.B")
	})

	t.Run("ProvidesDotGraph", func(t *testing.T) {
		type A struct{}
		type B struct{}
		type C struct{}
		var g DotGraph
		app := fxtest.New(t,
			Provide(func() A { return A{} }),
			Provide(func(A) B { return B{} }),
			Provide(func(A, B) C { return C{} }),
			Populate(&g),
		)
		defer app.RequireStart().RequireStop()
		require.NoError(t, app.Err())
		assert.Contains(t, g, `"fx.DotGraph" [label=<fx.DotGraph>];`)
	})

	t.Run("ProvidesWithAnnotate", func(t *testing.T) {
		type A struct{}

		type B struct {
			In

			Foo  A   `name:"foo"`
			Bar  A   `name:"bar"`
			Foos []A `group:"foo"`
		}

		app := fxtest.New(t,
			Provide(
				Annotated{
					Target: func() A { return A{} },
					Name:   "foo",
				},
				Annotated{
					Target: func() A { return A{} },
					Name:   "bar",
				},
				Annotated{
					Target: func() A { return A{} },
					Group:  "foo",
				},
			),
			Invoke(
				func(b B) {
					assert.NotNil(t, b.Foo)
					assert.NotNil(t, b.Bar)
					assert.Len(t, b.Foos, 1)
				},
			),
		)

		defer app.RequireStart().RequireStop()
		require.NoError(t, app.Err())
	})

	t.Run("ProvidesWithAnnotateFlattened", func(t *testing.T) {
		app := fxtest.New(t,
			Provide(Annotated{
				Target: func() []int { return []int{1} },
				Group:  "foo,flatten",
			}),
			Invoke(
				func(b struct {
					In
					Foos []int `group:"foo"`
				}) {
					assert.Len(t, b.Foos, 1)
				},
			),
		)

		defer app.RequireStart().RequireStop()
		require.NoError(t, app.Err())
	})

	t.Run("ProvidesWithEmptyAnnotate", func(t *testing.T) {
		type A struct{}

		type B struct {
			In

			Foo A
		}

		app := fxtest.New(t,
			Provide(
				Annotated{
					Target: func() A { return A{} },
				},
			),
			Invoke(
				func(b B) {
					assert.NotNil(t, b.Foo)
				},
			),
		)

		defer app.RequireStart().RequireStop()
		require.NoError(t, app.Err())
	})

	t.Run("CannotNameAndGroup", func(t *testing.T) {
		type A struct{}

		app := NewForTest(t,
			Provide(
				Annotated{
					Target: func() A { return A{} },
					Name:   "foo",
					Group:  "bar",
				},
			),
		)

		err := app.Err()
		require.Error(t, err)

		// fx.Annotated may specify only one of Name or Group: received fx.Annotated{Name: "foo", Group: "bar", Target: go.uber.org/fx_test.TestAnnotatedWithGroupAndName.func1()} from:
		// go.uber.org/fx_test.TestAnnotatedWithGroupAndName
		//         /.../fx/annotated_test.go:164
		// testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		assert.Contains(t, err.Error(), "fx.Annotated may specify only one of Name or Group:")
		assert.Contains(t, err.Error(), `received fx.Annotated{Name: "foo", Group: "bar", Target: go.uber.org/fx_test.TestNewApp`)
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestNewApp")
		assert.Contains(t, err.Error(), "fx/app_test.go")
	})

	t.Run("ErrorProvidingAnnotated", func(t *testing.T) {
		app := NewForTest(t, Provide(Annotated{
			Target: 42, // not a constructor
			Name:   "foo",
		}))

		err := app.Err()
		require.Error(t, err)

		// Example:
		// fx.Provide(fx.Annotated{...}) from:
		//     go.uber.org/fx_test.TestNewApp.func8
		//         /.../fx/app_test.go:206
		//     testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		//     Failed: must provide constructor function, got 42 (type int)
		assert.Contains(t, err.Error(), `fx.Provide(fx.Annotated{Name: "foo", Target: 42}) from:`)
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestNewApp")
		assert.Contains(t, err.Error(), "fx/app_test.go")
		assert.Contains(t, err.Error(), "Failed: must provide constructor function")
	})

	t.Run("ErrorProviding", func(t *testing.T) {
		err := NewForTest(t, Provide(42)).Err()
		require.Error(t, err)

		// Example:
		// fx.Provide(..) from:
		//     go.uber.org/fx_test.TestNewApp.func8
		//         /.../fx/app_test.go:206
		//     testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		//     Failed: must provide constructor function, got 42 (type int)
		assert.Contains(t, err.Error(), "fx.Provide(42) from:")
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestNewApp")
		assert.Contains(t, err.Error(), "fx/app_test.go")
		assert.Contains(t, err.Error(), "Failed: must provide constructor function")
	})
}

type errHandlerFunc func(error)

func (f errHandlerFunc) HandleError(err error) { f(err) }

func TestInvokes(t *testing.T) {
	t.Run("ErrorsAreNotOverriden", func(t *testing.T) {
		type A struct{}
		type B struct{}

		app := NewForTest(t,
			Provide(func() B { return B{} }), // B inserted into the graph
			Invoke(func(A) {}),               // failed A invoke
			Invoke(func(B) {}),               // successful B invoke
		)
		err := app.Err()
		require.Error(t, err)
		assert.Contains(t, err.Error(), "missing type: fx_test.A")
	})

	t.Run("ErrorHooksAreCalled", func(t *testing.T) {
		type A struct{}

		count := 0
		h := errHandlerFunc(func(err error) {
			count++
		})
		NewForTest(t,
			Invoke(func(A) {}),
			ErrorHook(h),
		)
		assert.Equal(t, 1, count)
	})
}

func TestError(t *testing.T) {
	t.Run("NilErrorOption", func(t *testing.T) {
		var invoked bool

		app := NewForTest(t,
			Error(nil),
			Invoke(func() { invoked = true }),
		)
		err := app.Err()
		require.NoError(t, err)
		assert.True(t, invoked)
	})

	t.Run("SingleErrorOption", func(t *testing.T) {
		app := NewForTest(t,
			Error(errors.New("module failure")),
			Invoke(func() { t.Errorf("Invoke should not be called") }),
		)
		err := app.Err()
		assert.EqualError(t, err, "module failure")
	})

	t.Run("MultipleErrorOption", func(t *testing.T) {
		type A struct{}

		app := NewForTest(t,
			Provide(func() A {
				t.Errorf("Provide should not be called")
				return A{}
			},
			),
			Invoke(func(A) { t.Errorf("Invoke should not be called") }),
			Error(
				errors.New("module A failure"),
				errors.New("module B failure"),
			),
		)
		err := app.Err()
		require.Error(t, err)
		assert.Contains(t, err.Error(), "module A failure")
		assert.Contains(t, err.Error(), "module B failure")
		assert.NotContains(t, err.Error(), "not in the container")
	})

	t.Run("ProvideAndInvokeErrorsAreIgnored", func(t *testing.T) {
		type A struct{}
		type B struct{}

		app := NewForTest(t,
			Provide(func(b B) A {
				t.Errorf("B is missing from the container; Provide should not be called")
				return A{}
			},
			),
			Error(errors.New("module failure")),
			Invoke(func(A) { t.Errorf("A was not provided; Invoke should not be called") }),
		)
		err := app.Err()
		assert.EqualError(t, err, "module failure")
	})
}

func TestOptions(t *testing.T) {
	t.Run("OptionsComposition", func(t *testing.T) {
		var n int
		construct := func() struct{} {
			n++
			return struct{}{}
		}
		use := func(struct{}) {
			n++
		}
		app := fxtest.New(t, Options(Provide(construct), Invoke(use)))
		defer app.RequireStart().RequireStop()
		assert.Equal(t, 2, n)
	})

	t.Run("ProvidesCalledInGraphOrder", func(t *testing.T) {
		type type1 struct{}
		type type2 struct{}
		type type3 struct{}

		initOrder := 0
		new1 := func() type1 {
			initOrder++
			assert.Equal(t, 1, initOrder)
			return type1{}
		}
		new2 := func(type1) type2 {
			initOrder++
			assert.Equal(t, 2, initOrder)
			return type2{}
		}
		new3 := func(type1, type2) type3 {
			initOrder++
			assert.Equal(t, 3, initOrder)
			return type3{}
		}
		biz := func(s1 type1, s2 type2, s3 type3) {
			initOrder++
			assert.Equal(t, 4, initOrder)
		}
		app := fxtest.New(t,
			Provide(new1, new2, new3),
			Invoke(biz),
		)
		defer app.RequireStart().RequireStop()
		assert.Equal(t, 4, initOrder)
	})

	t.Run("ProvidesCalledLazily", func(t *testing.T) {
		count := 0
		newBuffer := func() *bytes.Buffer {
			t.Error("this module should not init: no provided type relies on it")
			return nil
		}
		newEmpty := func() struct{} {
			count++
			return struct{}{}
		}
		app := fxtest.New(t,
			Provide(newBuffer, newEmpty),
			Invoke(func(struct{}) { count++ }),
		)
		defer app.RequireStart().RequireStop()
		assert.Equal(t, 2, count)
	})

	t.Run("Error", func(t *testing.T) {
		spy := new(fxlog.Spy)
		New(
			Provide(&bytes.Buffer{}), // error, not a constructor
			Logger(spy),
		)
		assert.Contains(t, spy.String(), "must provide constructor function")
	})
}

func TestTimeoutOptions(t *testing.T) {
	const timeout = time.Minute
	// Further assertions can't succeed unless the test timeout is greater than the default.
	require.True(t, timeout > DefaultTimeout, "test assertions require timeout greater than default")

	var started, stopped bool
	assertCustomContext := func(ctx context.Context, phase string) {
		deadline, ok := ctx.Deadline()
		if assert.True(t, ok, "no %s deadline", phase) {
			remaining := time.Until(deadline)
			assert.True(t, remaining > DefaultTimeout, "didn't respect customized %s timeout", phase)
		}
	}
	verify := func(lc Lifecycle) {
		lc.Append(Hook{
			OnStart: func(ctx context.Context) error {
				assertCustomContext(ctx, "start")
				started = true
				return nil
			},
			OnStop: func(ctx context.Context) error {
				assertCustomContext(ctx, "stop")
				stopped = true
				return nil
			},
		})
	}
	app := fxtest.New(
		t,
		Invoke(verify),
		StartTimeout(timeout),
		StopTimeout(timeout),
	)

	app.RequireStart().RequireStop()
	assert.True(t, started, "app wasn't started")
	assert.True(t, stopped, "app wasn't stopped")
}

func TestAppStart(t *testing.T) {
	t.Run("Timeout", func(t *testing.T) {
		type A struct{}
		blocker := func(lc Lifecycle) *A {
			lc.Append(
				Hook{
					OnStart: func(context.Context) error {
						select {}
					},
				},
			)
			return &A{}
		}
		app := fxtest.New(
			t,
			Provide(blocker),
			Invoke(func(*A) {}),
		)

		ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond)
		defer cancel()

		err := app.Start(ctx)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "context deadline exceeded")
	})

	t.Run("StartError", func(t *testing.T) {
		failStart := func(lc Lifecycle) struct{} {
			lc.Append(Hook{OnStart: func(context.Context) error {
				return errors.New("OnStart fail")
			}})
			return struct{}{}
		}
		app := fxtest.New(t,
			Provide(failStart),
			Invoke(func(struct{}) {}),
		)
		err := app.Start(context.Background())
		require.Error(t, err)
		assert.Contains(t, err.Error(), "OnStart fail")
	})

	t.Run("StartAndStopErrors", func(t *testing.T) {
		errStop1 := errors.New("OnStop fail 1")
		errStart2 := errors.New("OnStart fail 2")
		fail := func(lc Lifecycle) struct{} {
			lc.Append(Hook{
				OnStart: func(context.Context) error { return nil },
				OnStop:  func(context.Context) error { return errStop1 },
			})
			lc.Append(Hook{
				OnStart: func(context.Context) error { return errStart2 },
				OnStop:  func(context.Context) error { assert.Fail(t, "should be never called"); return nil },
			})
			return struct{}{}
		}
		app := NewForTest(t,
			Provide(fail),
			Invoke(func(struct{}) {}),
		)
		err := app.Start(context.Background())
		require.Error(t, err)
		assert.Equal(t, []error{errStart2, errStop1}, multierr.Errors(err))
	})

	t.Run("InvokeNonFunction", func(t *testing.T) {
		spy := new(fxlog.Spy)

		app := New(Logger(spy), Invoke(struct{}{}))
		err := app.Err()
		require.Error(t, err, "expected start failure")
		assert.Contains(t, err.Error(), "can't invoke non-function")

		// Example
		// fx.Invoke({}) called from:
		// go.uber.org/fx_test.TestAppStart.func4
		//         /.../fx/app_test.go:525
		// testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		// Failed: can't invoke non-function {} (type struct {})
		output := spy.String()
		assert.Contains(t, output, "fx.Invoke({}) called from:")
		assert.Contains(t, output, "go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, output, "fx/app_test.go")
		assert.Contains(t, output, "Failed: can't invoke non-function")
	})

	t.Run("ProvidingAProvideShouldFail", func(t *testing.T) {
		type type1 struct{}
		type type2 struct{}
		type type3 struct{}

		app := NewForTest(t,
			Provide(
				func() type1 { return type1{} },
				Provide(
					func() type2 { return type2{} },
					func() type3 { return type3{} },
				),
			),
		)

		err := app.Err()
		require.Error(t, err, "expected start failure")

		// Example:
		// fx.Option should be passed to fx.New directly, not to fx.Provide: fx.Provide received fx.Provide(go.uber.org/fx_test.TestAppStart.func5.2(), go.uber.org/fx_test.TestAppStart.func5.3()) from:
		// go.uber.org/fx_test.TestAppStart.func5
		//         /.../fx/app_test.go:550
		// testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		assert.Contains(t, err.Error(), "fx.Option should be passed to fx.New directly, not to fx.Provide")
		assert.Contains(t, err.Error(), "fx.Provide received fx.Provide(go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "fx/app_test.go")
	})

	t.Run("InvokingAnInvokeShouldFail", func(t *testing.T) {
		type type1 struct{}

		app := NewForTest(t,
			Provide(func() type1 { return type1{} }),
			Invoke(Invoke(func(type1) {
			})),
		)
		newErr := app.Err()
		require.Error(t, newErr)

		err := app.Start(context.Background())
		require.Error(t, err, "expected start failure")
		assert.Equal(t, err, newErr, "start should return the same error fx.New encountered")

		// Example
		// fx.Option should be passed to fx.New directly, not to fx.Invoke: fx.Invoke received fx.Invoke(go.uber.org/fx_test.TestAppStart.func6.2()) from:
		// go.uber.org/fx_test.TestAppStart.func6
		//         /.../fx/app_test.go:579
		// testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		assert.Contains(t, err.Error(), "fx.Option should be passed to fx.New directly, not to fx.Invoke")
		assert.Contains(t, err.Error(), "fx.Invoke received fx.Invoke(go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "/fx/app_test.go")
	})

	t.Run("ProvidingOptionsShouldFail", func(t *testing.T) {
		type type1 struct{}
		type type2 struct{}
		type type3 struct{}

		module := Options(
			Provide(
				func() type1 { return type1{} },
				func() type2 { return type2{} },
			),
			Invoke(func(type1) {
				require.FailNow(t, "module Invoke must not be called")
			}),
		)

		app := NewForTest(t,
			Provide(
				func() type3 { return type3{} },
				module,
			),
		)
		err := app.Err()
		require.Error(t, err, "expected start failure")

		// Example:
		// fx.Annotated should be passed to fx.Provide directly, it should not be returned by the constructor: fx.Provide received go.uber.org/fx_test.TestAnnotatedWrongUsage.func2.1() from:
		// go.uber.org/fx_test.TestAnnotatedWrongUsage.func2
		//         /.../fx/annotated_test.go:76
		// testing.tRunner
		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
		assert.Contains(t, err.Error(), "fx.Option should be passed to fx.New directly, not to fx.Provide")
		assert.Contains(t, err.Error(), "fx.Provide received fx.Options(fx.Provide(go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestAppStart")
		assert.Contains(t, err.Error(), "fx/app_test.go")
	})
}

func TestAppStop(t *testing.T) {
	t.Run("Timeout", func(t *testing.T) {
		block := func(context.Context) error { select {} }
		app := fxtest.New(t, Invoke(func(l Lifecycle) {
			l.Append(Hook{OnStop: block})
		}))
		app.RequireStart()

		ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond)
		defer cancel()

		err := app.Stop(ctx)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "context deadline exceeded")
	})

	t.Run("StopError", func(t *testing.T) {
		failStop := func(lc Lifecycle) struct{} {
			lc.Append(Hook{OnStop: func(context.Context) error {
				return errors.New("OnStop fail")
			}})
			return struct{}{}
		}
		app := fxtest.New(t,
			Provide(failStop),
			Invoke(func(struct{}) {}),
		)
		app.RequireStart()
		err := app.Stop(context.Background())
		require.Error(t, err)
		assert.Contains(t, err.Error(), "OnStop fail")
	})
}

func TestDone(t *testing.T) {
	done := fxtest.New(t).Done()
	require.NotNil(t, done, "Got a nil channel.")
	select {
	case sig := <-done:
		t.Fatalf("Got unexpected signal %v from application's Done channel.", sig)
	default:
	}
}

func TestReplaceLogger(t *testing.T) {
	spy := new(fxlog.Spy)
	app := fxtest.New(t, Logger(spy))
	app.RequireStart().RequireStop()
	assert.Contains(t, spy.String(), "RUNNING")
}

func TestNopLogger(t *testing.T) {
	app := fxtest.New(t, NopLogger)
	app.RequireStart().RequireStop()
}

type testErrorWithGraph struct {
	graph string
}

func (we testErrorWithGraph) Graph() DotGraph {
	return DotGraph(we.graph)
}

func (we testErrorWithGraph) Error() string {
	return "great sadness"
}

func TestVisualizeError(t *testing.T) {
	t.Run("NotWrappedError", func(t *testing.T) {
		_, err := VisualizeError(errors.New("great sadness"))
		require.Error(t, err)
	})

	t.Run("WrappedErrorWithEmptyGraph", func(t *testing.T) {
		graph, err := VisualizeError(testErrorWithGraph{graph: ""})
		assert.Empty(t, graph)
		require.Error(t, err)
	})

	t.Run("WrappedError", func(t *testing.T) {
		graph, err := VisualizeError(testErrorWithGraph{graph: "graph"})
		assert.Equal(t, "graph", graph)
		require.NoError(t, err)
	})
}

func TestErrorHook(t *testing.T) {
	t.Run("UnvisualizableError", func(t *testing.T) {
		type A struct{}

		var graphErr error
		h := errHandlerFunc(func(err error) {
			_, graphErr = VisualizeError(err)
		})
		NewForTest(t,
			Provide(func() A { return A{} }),
			Invoke(func(A) error { return errors.New("great sadness") }),
			ErrorHook(h),
		)
		assert.Equal(t, errors.New("unable to visualize error"), graphErr)
	})

	t.Run("GraphWithError", func(t *testing.T) {
		type A struct{}
		type B struct{}
		type C struct{}

		var errStr, graphStr string
		h := errHandlerFunc(func(err error) {
			errStr = err.Error()
			graphStr, _ = VisualizeError(err)
		})
		NewForTest(t,
			Provide(func() (B, error) { return B{}, fmt.Errorf("great sadness") }),
			Provide(func(B) A { return A{} }),
			Invoke(func(A) {}),
			ErrorHook(&h),
		)
		assert.Contains(t, errStr, "great sadness")
		assert.Contains(t, graphStr, `"fx_test.B" [color=red];`)
		assert.Contains(t, graphStr, `"fx_test.A" [color=orange];`)
	})
}

func TestOptionString(t *testing.T) {
	tests := []struct {
		desc string
		give Option
		want string
	}{
		{
			desc: "Provide",
			give: Provide(bytes.NewReader),
			want: "fx.Provide(bytes.NewReader())",
		},
		{
			desc: "Invoke",
			give: Invoke(func(c io.Closer) error {
				return c.Close()
			}),
			want: "fx.Invoke(go.uber.org/fx_test.TestOptionString.func1())",
		},
		{
			desc: "Error/single",
			give: Error(errors.New("great sadness")),
			want: "fx.Error(great sadness)",
		},
		{
			desc: "Error/multiple",
			give: Error(errors.New("foo"), errors.New("bar")),
			want: "fx.Error(foo; bar)",
		},
		{
			desc: "Options/single",
			give: Options(Provide(bytes.NewBuffer)),
			// NOTE: We don't prune away fx.Options for the empty
			// case because we want to attach additional
			// information to the fx.Options object in the future.
			want: "fx.Options(fx.Provide(bytes.NewBuffer()))",
		},
		{
			desc: "Options/multiple",
			give: Options(
				Provide(bytes.NewBufferString),
				Invoke(func(buf *bytes.Buffer) {
					buf.WriteString("hello")
				}),
			),
			want: "fx.Options(" +
				"fx.Provide(bytes.NewBufferString()), " +
				"fx.Invoke(go.uber.org/fx_test.TestOptionString.func2())" +
				")",
		},
		{
			desc: "StartTimeout",
			give: StartTimeout(time.Second),
			want: "fx.StartTimeout(1s)",
		},
		{
			desc: "StopTimeout",
			give: StopTimeout(5 * time.Second),
			want: "fx.StopTimeout(5s)",
		},
		{
			desc: "Logger",
			give: Logger(testLogger{t}),
			want: "fx.Logger(TestOptionString)",
		},
		{
			desc: "NopLogger",
			give: NopLogger,
			want: "fx.Logger(NopLogger)",
		},
		{
			desc: "ErrorHook",
			give: ErrorHook(testErrorHandler{t}),
			want: "fx.ErrorHook(TestOptionString)",
		},
		{
			desc: "Supply/simple",
			give: Supply(bytes.NewReader(nil), bytes.NewBuffer(nil)),
			want: "fx.Supply(*bytes.Reader, *bytes.Buffer)",
		},
		{
			desc: "Supply/Annotated",
			give: Supply(Annotated{Target: bytes.NewReader(nil)}),
			want: "fx.Supply(*bytes.Reader)",
		},
	}

	for _, tt := range tests {
		t.Run(tt.desc, func(t *testing.T) {
			stringer, ok := tt.give.(fmt.Stringer)
			require.True(t, ok, "option must implement stringer")
			assert.Equal(t, tt.want, stringer.String())
		})
	}
}

type testLogger struct{ t *testing.T }

func (l testLogger) Printf(s string, args ...interface{}) {
	l.t.Logf(s, args...)
}

func (l testLogger) String() string {
	return l.t.Name()
}

type testErrorHandler struct{ t *testing.T }

func (h testErrorHandler) HandleError(err error) {
	h.t.Error(err)
}

func (h testErrorHandler) String() string {
	return h.t.Name()
}