How to use out method of main Package

...31	name       string32	renamedPkg string33	pkg        string34	in         string35	out        string36	broken     bool // known broken37}38var addTests = []test{39	{40		name: "leave os alone",41		pkg:  "os",42		in: `package main43import (44	"os"45)46`,47		out: `package main48import (49	"os"50)51`,52	},53	{54		name: "import.1",55		pkg:  "os",56		in: `package main57`,58		out: `package main59import "os"60`,61	},62	{63		name: "import.2",64		pkg:  "os",65		in: `package main66// Comment67import "C"68`,69		out: `package main70// Comment71import "C"72import "os"73`,74	},75	{76		name: "import.3",77		pkg:  "os",78		in: `package main79// Comment80import "C"81import (82	"io"83	"utf8"84)85`,86		out: `package main87// Comment88import "C"89import (90	"io"91	"os"92	"utf8"93)94`,95	},96	{97		name: "import.17",98		pkg:  "x/y/z",99		in: `package main100// Comment101import "C"102import (103	"a"104	"b"105	"x/w"106	"d/f"107)108`,109		out: `package main110// Comment111import "C"112import (113	"a"114	"b"115	"x/w"116	"x/y/z"117	"d/f"118)119`,120	},121	{122		name: "import into singular group",123		pkg:  "bytes",124		in: `package main125import "os"126`,127		out: `package main128import (129	"bytes"130	"os"131)132`,133	},134	{135		name: "import into singular group with comment",136		pkg:  "bytes",137		in: `package main138import /* why */ /* comment here? */ "os"139`,140		out: `package main141import /* why */ /* comment here? */ (142	"bytes"143	"os"144)145`,146	},147	{148		name: "import into group with leading comment",149		pkg:  "strings",150		in: `package main151import (152	// comment before bytes153	"bytes"154	"os"155)156`,157		out: `package main158import (159	// comment before bytes160	"bytes"161	"os"162	"strings"163)164`,165	},166	{167		name:       "",168		renamedPkg: "fmtpkg",169		pkg:        "fmt",170		in: `package main171import "os"172`,173		out: `package main174import (175	fmtpkg "fmt"176	"os"177)178`,179	},180	{181		name: "struct comment",182		pkg:  "time",183		in: `package main184// This is a comment before a struct.185type T struct {186	t  time.Time187}188`,189		out: `package main190import "time"191// This is a comment before a struct.192type T struct {193	t time.Time194}195`,196	},197	{198		name: "issue 8729 import C",199		pkg:  "time",200		in: `package main201import "C"202// comment203type T time.Time204`,205		out: `package main206import "C"207import "time"208// comment209type T time.Time210`,211	},212	{213		name: "issue 8729 empty import",214		pkg:  "time",215		in: `package main216import ()217// comment218type T time.Time219`,220		out: `package main221import "time"222// comment223type T time.Time224`,225	},226	{227		name: "issue 8729 comment on package line",228		pkg:  "time",229		in: `package main // comment230type T time.Time231`,232		out: `package main // comment233import "time"234type T time.Time235`,236	},237	{238		name: "issue 8729 comment after package",239		pkg:  "time",240		in: `package main241// comment242type T time.Time243`,244		out: `package main245import "time"246// comment247type T time.Time248`,249	},250	{251		name: "issue 8729 comment before and on package line",252		pkg:  "time",253		in: `// comment before254package main // comment on255type T time.Time256`,257		out: `// comment before258package main // comment on259import "time"260type T time.Time261`,262	},263	// Issue 9961: Match prefixes using path segments rather than bytes264	{265		name: "issue 9961",266		pkg:  "regexp",267		in: `package main268import (269	"flag"270	"testing"271	"rsc.io/p"272)273`,274		out: `package main275import (276	"flag"277	"regexp"278	"testing"279	"rsc.io/p"280)281`,282	},283}284func TestAddImport(t *testing.T) {285	for _, test := range addTests {286		file := parse(t, test.name, test.in)287		var before bytes.Buffer288		ast.Fprint(&before, fset, file, nil)289		AddNamedImport(fset, file, test.renamedPkg, test.pkg)290		if got := print(t, test.name, file); got != test.out {291			if test.broken {292				t.Logf("%s is known broken:\ngot: %s\nwant: %s", test.name, got, test.out)293			} else {294				t.Errorf("%s:\ngot: %s\nwant: %s", test.name, got, test.out)295			}296			var after bytes.Buffer297			ast.Fprint(&after, fset, file, nil)298			t.Logf("AST before:\n%s\nAST after:\n%s\n", before.String(), after.String())299		}300	}301}302func TestDoubleAddImport(t *testing.T) {303	file := parse(t, "doubleimport", "package main\n")304	AddImport(fset, file, "os")305	AddImport(fset, file, "bytes")306	want := `package main307import (308	"bytes"309	"os"310)311`312	if got := print(t, "doubleimport", file); got != want {313		t.Errorf("got: %s\nwant: %s", got, want)314	}315}316// Part of issue 8729.317func TestDoubleAddImportWithDeclComment(t *testing.T) {318	file := parse(t, "doubleimport", `package main319import (320)321// comment322type I int323`)324	// The AddImport order here matters.325	AddImport(fset, file, "llvm.org/llgo/third_party/gotools/go/ast/astutil")326	AddImport(fset, file, "os")327	want := `package main328import (329	"llvm.org/llgo/third_party/gotools/go/ast/astutil"330	"os"331)332// comment333type I int334`335	if got := print(t, "doubleimport_with_decl_comment", file); got != want {336		t.Errorf("got: %s\nwant: %s", got, want)337	}338}339var deleteTests = []test{340	{341		name: "import.4",342		pkg:  "os",343		in: `package main344import (345	"os"346)347`,348		out: `package main349`,350	},351	{352		name: "import.5",353		pkg:  "os",354		in: `package main355// Comment356import "C"357import "os"358`,359		out: `package main360// Comment361import "C"362`,363	},364	{365		name: "import.6",366		pkg:  "os",367		in: `package main368// Comment369import "C"370import (371	"io"372	"os"373	"utf8"374)375`,376		out: `package main377// Comment378import "C"379import (380	"io"381	"utf8"382)383`,384	},385	{386		name: "import.7",387		pkg:  "io",388		in: `package main389import (390	"io"   // a391	"os"   // b392	"utf8" // c393)394`,395		out: `package main396import (397	// a398	"os"   // b399	"utf8" // c400)401`,402	},403	{404		name: "import.8",405		pkg:  "os",406		in: `package main407import (408	"io"   // a409	"os"   // b410	"utf8" // c411)412`,413		out: `package main414import (415	"io" // a416	// b417	"utf8" // c418)419`,420	},421	{422		name: "import.9",423		pkg:  "utf8",424		in: `package main425import (426	"io"   // a427	"os"   // b428	"utf8" // c429)430`,431		out: `package main432import (433	"io" // a434	"os" // b435	// c436)437`,438	},439	{440		name: "import.10",441		pkg:  "io",442		in: `package main443import (444	"io"445	"os"446	"utf8"447)448`,449		out: `package main450import (451	"os"452	"utf8"453)454`,455	},456	{457		name: "import.11",458		pkg:  "os",459		in: `package main460import (461	"io"462	"os"463	"utf8"464)465`,466		out: `package main467import (468	"io"469	"utf8"470)471`,472	},473	{474		name: "import.12",475		pkg:  "utf8",476		in: `package main477import (478	"io"479	"os"480	"utf8"481)482`,483		out: `package main484import (485	"io"486	"os"487)488`,489	},490	{491		name: "handle.raw.quote.imports",492		pkg:  "os",493		in:   "package main\n\nimport `os`",494		out: `package main495`,496	},497	{498		name: "import.13",499		pkg:  "io",500		in: `package main501import (502	"fmt"503	"io"504	"os"505	"utf8"506	"go/format"507)508`,509		out: `package main510import (511	"fmt"512	"os"513	"utf8"514	"go/format"515)516`,517	},518	{519		name: "import.14",520		pkg:  "io",521		in: `package main522import (523	"fmt" // a524	"io"   // b525	"os"   // c526	"utf8" // d527	"go/format" // e528)529`,530		out: `package main531import (532	"fmt" // a533	// b534	"os"   // c535	"utf8" // d536	"go/format" // e537)538`,539	},540	{541		name: "import.15",542		pkg:  "double",543		in: `package main544import (545	"double"546	"double"547)548`,549		out: `package main550`,551	},552	{553		name: "import.16",554		pkg:  "bubble",555		in: `package main556import (557	"toil"558	"bubble"559	"bubble"560	"trouble"561)562`,563		out: `package main564import (565	"toil"566	"trouble"567)568`,569	},570	{571		name: "import.17",572		pkg:  "quad",573		in: `package main574import (575	"quad"576	"quad"577)578import (579	"quad"580	"quad"581)582`,583		out: `package main584`,585	},586}587func TestDeleteImport(t *testing.T) {588	for _, test := range deleteTests {589		file := parse(t, test.name, test.in)590		DeleteImport(fset, file, test.pkg)591		if got := print(t, test.name, file); got != test.out {592			t.Errorf("%s:\ngot: %s\nwant: %s", test.name, got, test.out)593		}594	}595}596type rewriteTest struct {597	name   string598	srcPkg string599	dstPkg string600	in     string601	out    string602}603var rewriteTests = []rewriteTest{604	{605		name:   "import.13",606		srcPkg: "utf8",607		dstPkg: "encoding/utf8",608		in: `package main609import (610	"io"611	"os"612	"utf8" // thanks ken613)614`,615		out: `package main616import (617	"encoding/utf8" // thanks ken618	"io"619	"os"620)621`,622	},623	{624		name:   "import.14",625		srcPkg: "asn1",626		dstPkg: "encoding/asn1",627		in: `package main628import (629	"asn1"630	"crypto"631	"crypto/rsa"632	_ "crypto/sha1"633	"crypto/x509"634	"crypto/x509/pkix"635	"time"636)637var x = 1638`,639		out: `package main640import (641	"crypto"642	"crypto/rsa"643	_ "crypto/sha1"644	"crypto/x509"645	"crypto/x509/pkix"646	"encoding/asn1"647	"time"648)649var x = 1650`,651	},652	{653		name:   "import.15",654		srcPkg: "url",655		dstPkg: "net/url",656		in: `package main657import (658	"bufio"659	"net"660	"path"661	"url"662)663var x = 1 // comment on x, not on url664`,665		out: `package main666import (667	"bufio"668	"net"669	"net/url"670	"path"671)672var x = 1 // comment on x, not on url673`,674	},675	{676		name:   "import.16",677		srcPkg: "http",678		dstPkg: "net/http",679		in: `package main680import (681	"flag"682	"http"683	"log"684	"text/template"685)686var addr = flag.String("addr", ":1718", "http service address") // Q=17, R=18687`,688		out: `package main689import (690	"flag"691	"log"692	"net/http"693	"text/template"694)695var addr = flag.String("addr", ":1718", "http service address") // Q=17, R=18696`,697	},698}699func TestRewriteImport(t *testing.T) {700	for _, test := range rewriteTests {701		file := parse(t, test.name, test.in)702		RewriteImport(fset, file, test.srcPkg, test.dstPkg)703		if got := print(t, test.name, file); got != test.out {704			t.Errorf("%s:\ngot: %s\nwant: %s", test.name, got, test.out)705		}706	}707}708var importsTests = []struct {709	name string710	in   string711	want [][]string712}{713	{714		name: "no packages",715		in: `package foo716`,717		want: nil,718	},...

1import "fmt"2func main() {3    fmt.Println("hello world")4}5import "fmt"6func main() {7    fmt.Println("hello world")8}9import "fmt"10func main() {11    fmt.Println("hello world")12}13import "fmt"14func main() {15    fmt.Println("hello world")16}17import "fmt"18func main() {19    fmt.Println("hello world")20}21import "fmt"22func main() {23    fmt.Println("hello world")24}25import "fmt"26func main() {27    fmt.Println("hello world")28}29import "fmt"30func main() {31    fmt.Println("hello world")32}33import "fmt"34func main() {35    fmt.Println("hello world")36}37import "fmt"38func main() {39    fmt.Println("hello world")40}41import "fmt"42func main() {43    fmt.Println("hello world")44}45import "fmt"46func main() {47    fmt.Println("hello world")48}49import "fmt"50func main() {51    fmt.Println("hello world")52}53import "fmt"54func main() {55    fmt.Println("hello world")56}

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