cmd/wire: add a --header_file flag to the "gen" and "diff" commands (#175)

internal/check_api_change.sh

@@ -52,7 +52,7 @@ trap cleanup EXIT
 git clone -b "$UPSTREAM_BRANCH" . "$MASTER_CLONE_DIR" &> /dev/null
 
 incompatible_change_pkgs=()
-PKGS=$(cd "$MASTER_CLONE_DIR"; go list ./... | grep -v test)
+PKGS=$(cd "$MASTER_CLONE_DIR"; go list ./... | grep -v test | grep -v internal)
 for pkg in $PKGS; do
   echo "  Testing ${pkg}..."
 

internal/wire/testdata/Header/foo/foo.go

@@ -0,0 +1,29 @@
+// Copyright 2019 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println(injectFoo())
+}
+
+type Foo int
+
+func provideFoo() Foo {
+	return 41
+}

internal/wire/testdata/Header/foo/wire.go

@@ -0,0 +1,26 @@
+// Copyright 2019 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//+build wireinject
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+func injectFoo() Foo {
+	wire.Build(provideFoo)
+	return Foo(0)
+}

internal/wire/testdata/Header/header

@@ -0,0 +1,2 @@
+// This is a sample header file.
+//

internal/wire/testdata/Header/pkg

@@ -0,0 +1 @@
+example.com/foo

internal/wire/testdata/Header/want/program_out.txt

@@ -0,0 +1 @@
+41

internal/wire/testdata/Header/want/wire_gen.go

@@ -0,0 +1,15 @@
+// This is a sample header file.
+//
+// Code generated by Wire. DO NOT EDIT.
+
+//go:generate wire
+//+build !wireinject
+
+package main
+
+// Injectors from wire.go:
+
+func injectFoo() Foo {
+	foo := provideFoo()
+	return foo
+}

internal/wire/wire.go

@@ -60,6 +60,12 @@ func (gen GenerateResult) Commit() error {
 	return ioutil.WriteFile(gen.OutputPath, gen.Content, 0666)
 }
 
+// GenerateOptions holds options for Generate.
+type GenerateOptions struct {
+	// Header will be inserted at the start of each generated file.
+	Header []byte
+}
+
 // Generate performs dependency injection for the packages that match the given
 // patterns, return a GenerateResult for each package. The package pattern is
 // defined by the underlying build system. For the go tool, this is described at
@@ -72,7 +78,10 @@ func (gen GenerateResult) Commit() error {
 // takes precedence.
 //
 // Generate may return one or more errors if it failed to load the packages.
-func Generate(ctx context.Context, wd string, env []string, patterns []string) ([]GenerateResult, []error) {
+func Generate(ctx context.Context, wd string, env []string, patterns []string, opts *GenerateOptions) ([]GenerateResult, []error) {
+	if opts == nil {
+		opts = &GenerateOptions{}
+	}
 	pkgs, errs := load(ctx, wd, env, patterns)
 	if len(errs) > 0 {
 		return nil, errs
@@ -94,6 +103,9 @@ func Generate(ctx context.Context, wd string, env []string, patterns []string) (
 		}
 		copyNonInjectorDecls(g, injectorFiles, pkg.TypesInfo)
 		goSrc := g.frame()
+		if len(opts.Header) > 0 {
+			goSrc = append(opts.Header, goSrc...)
+		}
 		fmtSrc, err := format.Source(goSrc)
 		if err != nil {
 			// This is likely a bug from a poorly generated source file.

internal/wire/wire_test.go

@@ -90,7 +90,7 @@ func TestWire(t *testing.T) {
 				t.Fatal(err)
 			}
 			wd := filepath.Join(gopath, "src", "example.com")
-			gens, errs := Generate(ctx, wd, append(os.Environ(), "GOPATH="+gopath), []string{test.pkg})
+			gens, errs := Generate(ctx, wd, append(os.Environ(), "GOPATH="+gopath), []string{test.pkg}, &GenerateOptions{Header: test.header})
 			var gen GenerateResult
 			if len(gens) > 1 {
 				t.Fatalf("got %d generated files, want 0 or 1", len(gens))
@@ -428,6 +428,7 @@ func scrubLineColumn(s string) (replacement string, n int) {
 type testCase struct {
 	name                 string
 	pkg                  string
+	header               []byte
 	goFiles              map[string][]byte
 	wantProgramOutput    []byte
 	wantWireOutput       []byte
@@ -471,6 +472,7 @@ func loadTestCase(root string, wireGoSrc []byte) (*testCase, error) {
 	if err != nil {
 		return nil, fmt.Errorf("load test case %s: %v", name, err)
 	}
+	header, _ := ioutil.ReadFile(filepath.Join(root, "header"))
 	var wantProgramOutput []byte
 	var wantWireOutput []byte
 	wireErrb, err := ioutil.ReadFile(filepath.Join(root, "want", "wire_errs.txt"))
@@ -521,6 +523,7 @@ func loadTestCase(root string, wireGoSrc []byte) (*testCase, error) {
 	return &testCase{
 		name:                 name,
 		pkg:                  string(bytes.TrimSpace(pkg)),
+		header:               header,
 		goFiles:              goFiles,
 		wantWireOutput:       wantWireOutput,
 		wantProgramOutput:    wantProgramOutput,