go.tools/astutil: make sure import blocks are marked as such (Lparen=1)

R=bradfitz
CC=golang-dev
https://golang.org/cl/22320044

astutil/imports.go

@@ -15,13 +15,6 @@ func AddImport(f *ast.File, ipath string) (added bool) {
 		return false
 	}
 
-	// Determine name of import.
-	// Assume added imports follow convention of using last element.
-	_, name := path.Split(ipath)
-
-	// Rename any conflicting top-level references from name to name_.
-	renameTop(f, name, name+"_")
-
 	newImport := &ast.ImportSpec{
 		Path: &ast.BasicLit{
 			Kind:  token.STRING,
@@ -88,6 +81,11 @@ func AddImport(f *ast.File, ipath string) (added bool) {
 		newImport.Path.ValuePos = prev.Pos()
 		newImport.EndPos = prev.Pos()
 	}
+	if len(impDecl.Specs) > 1 && impDecl.Lparen == 0 {
+		// set Lparen to something not zero, so the printer prints
+		// the full block rather just the first ImportSpec.
+		impDecl.Lparen = 1
+	}
 
 	f.Imports = append(f.Imports, newImport)
 	return true
@@ -240,9 +238,9 @@ func declImports(gen *ast.GenDecl, path string) bool {
 	return false
 }
 
-// renameTop renames all references to the top-level name old.
+// RenameTop renames all references to the top-level name old.
 // It returns true if it makes any changes.
-func renameTop(f *ast.File, old, new string) bool {
+func RenameTop(f *ast.File, old, new string) bool {
 	var fixed bool
 
 	// Rename any conflicting imports

astutil/imports_test.go

@@ -133,6 +133,22 @@ import (
 
 	"d/f"
 )
+`,
+	},
+	{
+		name: "import into singular block",
+		pkg:  "bytes",
+		in: `package main
+
+import "os"
+
+`,
+		out: `package main
+
+import (
+	"bytes"
+	"os"
+)
 `,
 	},
 }
@@ -147,6 +163,22 @@ func TestAddImport(t *testing.T) {
 	}
 }
 
+func TestDoubleAddImport(t *testing.T) {
+	file := parse(t, "doubleimport", "package main\n")
+	AddImport(file, "os")
+	AddImport(file, "bytes")
+	want := `package main
+
+import (
+	"bytes"
+	"os"
+)
+`
+	if got := print(t, "doubleimport", file); got != want {
+		t.Errorf("got: %s\nwant: %s", got, want)
+	}
+}
+
 var deleteTests = []test{
 	{
 		name: "import.4",
@@ -315,6 +347,13 @@ import (
 	"io"
 	"os"
 )
+`,
+	},
+	{
+		name: "handle.raw.quote.imports",
+		pkg:  "os",
+		in:   "package main\n\nimport `os`",
+		out: `package main
 `,
 	},
 }
@@ -457,3 +496,35 @@ func TestRewriteImport(t *testing.T) {
 		}
 	}
 }
+
+var renameTests = []rewriteTest{
+	{
+		name:   "rename pkg use",
+		srcPkg: "bytes",
+		dstPkg: "bytes_",
+		in: `package main
+
+func f() []byte {
+	buf := new(bytes.Buffer)
+	return buf.Bytes()
+}
+`,
+		out: `package main
+
+func f() []byte {
+	buf := new(bytes_.Buffer)
+	return buf.Bytes()
+}
+`,
+	},
+}
+
+func TestRenameTop(t *testing.T) {
+	for _, test := range renameTests {
+		file := parse(t, test.name, test.in)
+		RenameTop(file, test.srcPkg, test.dstPkg)
+		if got := print(t, test.name, file); got != test.out {
+			t.Errorf("%s:\ngot: %s\nwant: %s", test.name, got, test.out)
+		}
+	}
+}