cmd/go: add compatibility tests for go mod tidy -diff

For #27005
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Change-Id: I90ab8c21222ac2189abb40e8c8e7549e2d940dd2
Reviewed-on: https://go-review.googlesource.com/c/go/+/587941
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Matloob <[email protected]>

Author: samthanawalla

src/cmd/go/alldocs.go

@@ -35,9 +35,9 @@ to standard error.
 The -e flag causes tidy to attempt to proceed despite errors
 encountered while loading packages.
 
-The -diff flag causes tidy not to modify the files but instead print the
-necessary changes as a unified diff. It exits with a non-zero code
-if updates are needed.
+The -diff flag causes tidy not to modify go.mod or go.sum but
+instead print the necessary changes as a unified diff. It exits
+with a non-zero code if the diff is not empty.
 
 The -go flag causes tidy to update the 'go' directive in the go.mod
 file to the given version, which may change which module dependencies

src/cmd/go/internal/modcmd/tidy.go

@@ -898,7 +898,7 @@ func TidyGoSum(keep map[module.Version]bool) (before, after []byte) {
 	return before, after
 }
 
-// tidyGoSum will return a tidy version of the go.sum file.
+// tidyGoSum returns a tidy version of the go.sum file.
 // The goSum lock must be held.
 func tidyGoSum(data []byte, keep map[module.Version]bool) []byte {
 	if !goSum.overwrite {

src/cmd/go/internal/modfetch/fetch.go

@@ -155,9 +155,9 @@ type PackageOpts struct {
 	// packages.
 	Tidy bool
 
-	// TidyDiff, if true, analyzes the necessary changes to go.mod and go.sum
-	// to make them tidy. It does not modify these files, but exits with
-	// a non-zero code if updates are needed.
+	// TidyDiff, if true, causes tidy not to modify go.mod or go.sum but
+	// instead print the necessary changes as a unified diff. It exits
+	// with a non-zero code if the diff is not empty.
 	TidyDiff bool
 
 	// TidyCompatibleVersion is the oldest Go version that must be able to
@@ -445,7 +445,7 @@ func LoadPackages(ctx context.Context, opts PackageOpts, patterns ...string) (ma
 			if err != nil {
 				base.Fatal(err)
 			}
-			goModDiff := diff.Diff("current go.mod", currentGoMod, "tidy go.mod", updatedGoMod)
+			goModDiff := diff.Diff("current/go.mod", currentGoMod, "tidy/go.mod", updatedGoMod)
 
 			modfetch.TrimGoSum(keep)
 			// Dropping compatibility for 1.16 may result in a strictly smaller go.sum.
@@ -454,7 +454,7 @@ func LoadPackages(ctx context.Context, opts PackageOpts, patterns ...string) (ma
 				keep = keepSums(ctx, loaded, requirements, addBuildListZipSums)
 			}
 			currentGoSum, tidyGoSum := modfetch.TidyGoSum(keep)
-			goSumDiff := diff.Diff("current go.sum", currentGoSum, "tidy go.sum", tidyGoSum)
+			goSumDiff := diff.Diff("current/go.sum", currentGoSum, "tidy/go.sum", tidyGoSum)
 
 			if len(goModDiff) > 0 {
 				fmt.Println(string(goModDiff))

src/cmd/go/internal/modload/load.go

@@ -30,6 +30,17 @@ cp go.mod go.mod.orig
 go mod tidy
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -diff
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go list -m all
 cmp stdout m_all.txt
 
@@ -45,6 +56,17 @@ cp go.mod.orig go.mod
 go mod tidy -compat=1.17
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -compat=1.17 -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -compat=1.17 -diff
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go list -m all
 cmp stdout m_all.txt
 

src/cmd/go/testdata/script/mod_tidy_compat.txt

@@ -21,6 +21,12 @@ stderr '^go: example\.com/m imports\n\texample\.net/added: module example\.net/a
 
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/added: module example\.net/added@latest found \(v0\.3\.0, replaced by \./a1\), but does not contain package example\.net/added$'
 
 # When we run 'go mod tidy -e', we should proceed past the first error and follow
 # it with a second error describing the version discrepancy.
@@ -37,6 +43,20 @@ stderr '^go: example\.com/m imports\n\texample\.net/added: module example\.net/a
 
 cmp go.mod go.mod.tidy
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod go.mod.tidyResult
+[exec:patch] ! exists go.sum
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -e -diff
+[exec:patch] stdout 'diff current/go.mod tidy/go.mod'
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/added: module example\.net/added@latest found \(v0\.3\.0, replaced by \./a1\), but does not contain package example\.net/added\ngo: example\.net/added failed to load from any module,\n\tbut go 1\.16 would load it from example\.net/added@v0\.2\.0$'
+[exec:patch] ! stderr '\n\tgo mod tidy'
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -e -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] ! exists go.sum
 
 -- go.mod --
 module example.com/m

src/cmd/go/testdata/script/mod_tidy_compat_added.txt

@@ -27,6 +27,14 @@ stderr '\n\nTo proceed despite packages unresolved in go 1\.16:\n\tgo mod tidy -
 
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/indirect imports\n\texample\.net/ambiguous/nested/pkg loaded from example\.net/ambiguous/nested@v0\.1\.0,\n\tbut go 1.16 would fail to locate it:\n\tambiguous import: found package example\.net/ambiguous/nested/pkg in multiple modules:\n\texample\.net/ambiguous v0.1.0 \(.*\)\n\texample\.net/ambiguous/nested v0.1.0 \(.*\)\n\n'
+[exec:patch] stderr '\n\nTo proceed despite packages unresolved in go 1\.16:\n\tgo mod tidy -e\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
+
 
 # If we run 'go mod tidy -e', we should still save enough checksums to run
 # 'go list -m all' reproducibly with go 1.16, even though we can't list
@@ -36,6 +44,19 @@ go mod tidy -e
 ! stderr '\n\tgo mod tidy'
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -e -diff
+[exec:patch] ! stderr '\n\tgo mod tidy'
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -e -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go list -m all
 cmp stdout all-m.txt
 
@@ -60,6 +81,19 @@ go mod tidy -compat=1.17
 go list -m all
 cmp stdout all-m.txt
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -compat=1.17 -diff
+[exec:patch] ! stderr .
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -compat=1.17 -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go mod edit -go=1.16
 ! go list -m all
 stderr '^go: example\.net/indirect@v0\.1\.0 requires\n\texample\.net/ambiguous@v0\.1\.0: missing go\.sum entry for go\.mod file; to add it:\n\tgo mod download example\.net/ambiguous\n'

src/cmd/go/testdata/script/mod_tidy_compat_ambiguous.txt

@@ -21,12 +21,30 @@ stderr '^go: example\.com/m imports\n\texample\.net/deleted loaded from example\
 
 stderr '\n\nTo upgrade to the versions selected by go 1.16, leaving some packages unresolved:\n\tgo mod tidy -e -go=1\.16 && go mod tidy -e -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/deleted loaded from example\.net/deleted@v0\.1\.0,\n\tbut go 1\.16 would fail to locate it in example\.net/deleted@v0\.2\.0\n\n'
+[exec:patch] stderr '\n\nTo upgrade to the versions selected by go 1.16, leaving some packages unresolved:\n\tgo mod tidy -e -go=1\.16 && go mod tidy -e -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 # The suggested 'go mod tidy -e' command should proceed anyway.
 
 go mod tidy -e
 cmp go.mod go.mod.tidy
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod go.mod.tidyResult
+[exec:patch] ! exists go.sum
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -e -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -e -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] ! exists go.sum
 
 # In 'go 1.16' mode we should error out in the way we claimed.
 
@@ -39,9 +57,16 @@ go mod edit -go=1.16
 ! go list -deps -f $MODFMT example.com/m
 stderr '^go: updates to go\.mod needed; to update it:\n\tgo mod tidy$'
 
+[exec:patch] cp go.mod go.mod.orig
 ! go mod tidy
 stderr '^go: example\.com/m imports\n\texample\.net/deleted: module example\.net/deleted@latest found \(v0\.2\.0, replaced by \./d2\), but does not contain package example\.net/deleted$'
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/deleted: module example\.net/deleted@latest found \(v0\.2\.0, replaced by \./d2\), but does not contain package example\.net/deleted$'
 
 -- go.mod --
 module example.com/m

src/cmd/go/testdata/script/mod_tidy_compat_deleted.txt

@@ -37,6 +37,14 @@ stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=
 
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/lazy tested by\n\texample\.net/lazy.test imports\n\texample\.com/retract/incompatible loaded from example\.com/retract/incompatible@v1\.0\.0,\n\tbut go 1\.16 would select v2\.0\.0\+incompatible\n\n'
+[exec:patch] stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
+
 # The suggested '-compat' flag to ignore differences should silence the error
 # and leave go.mod unchanged, resulting in checksum errors when Go 1.16 tries
 # to load a module pruned out by Go 1.17.
@@ -45,6 +53,18 @@ go mod tidy -compat=1.17
 ! stderr .
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -compat=1.17 -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -compat=1.17 -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go list -deps -test -f $MODFMT ./...
 stdout '^example.net/lazy v0.1.0$'
 

src/cmd/go/testdata/script/mod_tidy_compat_implicit.txt

@@ -37,6 +37,13 @@ stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=
 
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! exists go.sum
+[exec:patch] ! go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] stderr '^go: example\.com/m imports\n\texample\.net/lazy imports\n\texample\.com/retract/incompatible loaded from example\.com/retract/incompatible@v1\.0\.0,\n\tbut go 1\.16 would select v2\.0\.0\+incompatible\n\n'
+[exec:patch] stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1\.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 # The suggested '-compat' flag to ignore differences should silence the error
 # and leave go.mod unchanged, resulting in checksum errors when Go 1.16 tries
@@ -46,6 +53,18 @@ go mod tidy -compat=1.17
 ! stderr .
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -compat=1.17 -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -compat=1.17 -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go mod edit -go=1.16
 ! go list -f $MODFMT -deps ./...
 stderr -count=1 '^go: example\.net/lazy@v0\.1\.0 requires\n\texample\.net/requireincompatible@v0\.1\.0 requires\n\texample\.com/retract/incompatible@v2\.0\.0\+incompatible: missing go.sum entry for go.mod file; to add it:\n\tgo mod download example.com/retract/incompatible$'

src/cmd/go/testdata/script/mod_tidy_compat_incompatible.txt

@@ -27,6 +27,18 @@ cp go.mod go.mod.orig
 go mod tidy
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] mv go.mod go.mod.tidyResult
+[exec:patch] mv go.sum go.sum.tidyResult
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] ! go mod tidy -diff
+[exec:patch] cp stdout diff.patch
+[exec:patch] exec patch -p1 -i diff.patch
+[exec:patch] go mod tidy -diff
+[exec:patch] ! stdout .
+[exec:patch] cmp go.mod go.mod.tidyResult
+[exec:patch] cmp go.sum go.sum.tidyResult
+
 go list -deps -test -f $MODFMT all
 cp stdout out-117.txt
 
@@ -42,6 +54,12 @@ cp go.mod.orig go.mod
 go mod tidy -compat=1.17
 cmp go.mod go.mod.orig
 
+# Make sure that -diff behaves the same as tidy.
+[exec:patch] cp go.mod.orig go.mod
+[exec:patch] rm go.sum
+[exec:patch] go mod tidy -compat=1.17 -diff
+[exec:patch] ! stdout .
+
 go list -deps -test -f $MODFMT all
 cmp stdout out-117.txt