go mod edit -go=1.499 -toolchain=none
go version
stdout go1.500-bigcorp

go mod edit -go=1.499 -toolchain=go1.499
go version
stdout go1.500-bigcorp

go mod edit -go=1.500 -toolchain=none
go version
stdout go1.500-bigcorp

go mod edit -go=1.500 -toolchain=go1.500
go version
stdout go1.500-bigcorp

go mod edit -go=1.501 -toolchain=none
go version
stdout go1.501

[short] skip
# Reset all experiments so fieldtrack is definitely off.
env GOEXPERIMENT=none
go run m
stderr 'fieldtrack off'
# Turn fieldtrack on.
env GOEXPERIMENT=none,fieldtrack
go run m
stderr 'fieldtrack on'

-- ft_off.go --
// +build !goexperiment.fieldtrack

package main

func main() {
	println("fieldtrack off")
}

-- ft_on.go --
// +build goexperiment.fieldtrack

package main

func main() {

// m.Version, or version "none" if no prior version is tagged.
//
// Since the version of a main module is not found in the version list,
// it has no previous version.
func previousVersion(ctx context.Context, m module.Version) (module.Version, error) {
	if m.Version == "" && MainModules.Contains(m.Path) {
		return module.Version{Path: m.Path, Version: "none"}, nil
	}

# Reverting the version should force a rebuild and error instead of using
# the cached 1.9 build. (https://golang.org/issue/37804)
go mod edit -go=1.8
! go build
stderr 'type alias requires'

# go=none should drop the line
go mod edit -go=none
! grep go go.mod

-- go.mod --
module m
go 1.8

-- alias.go --
package alias

env GOTOOLCHAIN=auto
rm go.mod
go mod init m
go mod edit -go=1.300 -toolchain=none
! go version
stderr 'go: downloading go1.300.0 '

rm go.mod
go mod init m
go mod edit -go=1.21 -toolchain=none
! go version
stderr 'go: downloading go1.21.0 '

rm go.mod
go mod init m
go mod edit -go=1.22 -toolchain=none
! go version
stderr 'go: downloading go1.22.0 '

rm go.mod
go mod init m

go list -m all
stdout '^example.com/a v0.1.0 '
stdout '^example.com/b v0.2.0 '
stdout '^example.com/c v0.1.0 '

# Removing c entirely should also remove the a and b that require it.

go get example.com/c@none
go list -m all
! stdout '^example.com/a '
! stdout '^example.com/b '
! stdout '^example.com/c '


# With lazy loading, downgrading c should work the same way, but dependencies

				t.Errorf("#%d: %q: expected error %q; got none", i, test.input, test.error)
			}
			continue
		}
		if !strings.Contains(err.Error(), test.error) {
			t.Errorf("#%d: expected error %q; got %q", i, test.error, err)
			continue
		}
	}
}

func runBadTest(i int, test badExprTest, t *testing.T) (err error) {
	p := NewParser(nil, nil, nil) // Expression evaluation uses none of these fields of the parser.

# GONOSUMDB bypasses sumdb, for rsc.io/quote, rsc.io/sampler, golang.org/x/text
env GONOSUMDB='*/quote,*/*mple*,golang.org/x'
go get rsc.io/quote
rm go.sum
env GOPRIVATE='*/quote,*/*mple*,golang.org/x'
env GONOPROXY=none # that is, proxy all despite GOPRIVATE
go get rsc.io/quote

# Download .info files needed for 'go list -m all' later.
# TODO(#42723): either 'go list -m' should not read these files,

env TESTGO_VERSION_SWITCH=switch

go get toolchain@go1.22.1
stderr '^go: added toolchain go1.22.1$'
! stderr '(added|removed|upgraded|downgraded) go'
grep 'toolchain go1.22.1' go.mod

go get toolchain@none
stderr '^go: removed toolchain go1.22.1$'
! stderr '(added|removed|upgraded|downgraded) go'
! grep toolchain go.mod

go get toolchain@go1.22.1
stderr '^go: added toolchain go1.22.1$'

go get toolchain@go1.22.1
go get toolchain@patch
stderr '^go: added toolchain go1.22.9$'
grep 'go 1.22.1' go.mod
grep 'toolchain go1.22.9' go.mod
go get go@1.22.9 toolchain@none
grep 'go 1.22.9' go.mod
! grep 'toolchain go1.22.9' go.mod

# go get toolchain@go1.24 does NOT find the release candidate
! go get toolchain@go1.24
stderr '^go: toolchain@go1.24: no matching versions for query "go1.24"$'