env TESTGO_VERSION=go1.21
env TESTGO_VERSION_SWITCH=switch

# First, test 'go mod download' outside of a module.
#
# There is no go.mod file into which we can record the selected toolchain,
# so unfortunately these version switches won't be as reproducible as other
# go commands, but that's still preferable to failing entirely or downloading
# a module zip that we don't understand.

# GOTOOLCHAIN=auto should run the newer toolchain
env GOTOOLCHAIN=auto
go mod download rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
stderr '^go: rsc.io/needall@v0.0.1 requires go >= 1.23; switching to go1.23.9$'
! stderr '\(running'

# GOTOOLCHAIN=min+auto should run the newer toolchain
env GOTOOLCHAIN=go1.21+auto
go mod download rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
stderr '^go: rsc.io/needall@v0.0.1 requires go >= 1.23; switching to go1.23.9$'
! stderr '\(running'

# GOTOOLCHAIN=go1.21 should NOT run the newer toolchain
env GOTOOLCHAIN=go1.21
! go mod download rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
! stderr switching
stderr 'rsc.io/needgo122@v0.0.1 requires go >= 1.22'
stderr 'rsc.io/needgo123@v0.0.1 requires go >= 1.23'
stderr 'rsc.io/needall@v0.0.1 requires go >= 1.23'
stderr 'requires go >= 1.23'
! stderr 'requires go >= 1.21' # that's us!


# JSON output should be emitted exactly once,
# and non-JSON output should go to stderr instead of stdout.
env GOTOOLCHAIN=auto
go mod download -json rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
stderr '^go: rsc.io/needall@v0.0.1 requires go >= 1.23; switching to go1.23.9$'
! stderr '\(running'
stdout -count=1 '"Path": "rsc.io/needgo121",'
stdout -count=1 '"Path": "rsc.io/needgo122",'
stdout -count=1 '"Path": "rsc.io/needgo123",'
stdout -count=1 '"Path": "rsc.io/needall",'

# GOTOOLCHAIN=go1.21 should write the errors in the JSON Error fields, not to stderr.
env GOTOOLCHAIN=go1.21
! go mod download -json rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
! stderr switching
stdout -count=1 '"Error": "rsc.io/needgo122@v0.0.1 requires go .*= 1.22 \(running go 1.21; GOTOOLCHAIN=go1.21\)"'
stdout -count=1 '"Error": "rsc.io/needgo123@v0.0.1 requires go .*= 1.23 \(running go 1.21; GOTOOLCHAIN=go1.21\)"'
stdout -count=1 '"Error": "rsc.io/needall@v0.0.1 requires go .*= 1.23 \(running go 1.21; GOTOOLCHAIN=go1.21\)"'
! stdout '"Error": "rsc.io/needgo121'  # We can handle this one.
! stderr .


# Within a module, 'go mod download' of explicit versions should upgrade if
# needed to perform the download, but should not change the main module's
# toolchain version (because the downloaded modules are still not required by
# the main module).

cd example
cp go.mod go.mod.orig

env GOTOOLCHAIN=auto
go mod download rsc.io/needgo121@latest rsc.io/needgo122@latest rsc.io/needgo123@latest rsc.io/needall@latest
stderr '^go: rsc.io/needall@v0.0.1 requires go >= 1.23; switching to go1.23.9$'
! stderr '\(running'
cmp go.mod go.mod.orig


# However, 'go mod download' without arguments should fix up the
# 'go' and 'toolchain' lines to be consistent with the existing
# requirements in the module graph.

go mod edit -require=rsc.io/needall@v0.0.1
cp go.mod go.mod.121

# If an upgrade is needed, GOTOOLCHAIN=go1.21 should cause
# the command to fail without changing go.mod.

env GOTOOLCHAIN=go1.21
! go mod download
stderr 'rsc.io/needall@v0.0.1 requires go >= 1.23'
! stderr switching
cmp go.mod go.mod.121

# If an upgrade is needed, GOTOOLCHAIN=auto should perform
# the upgrade and record the resulting toolchain version.

env GOTOOLCHAIN=auto
go mod download
stderr '^go: module rsc.io/needall@v0.0.1 requires go >= 1.23; switching to go1.23.9$'
cmp go.mod go.mod.final


-- example/go.mod --
module example

go 1.21
-- example/go.mod.final --
module example

go 1.23

toolchain go1.23.9

require rsc.io/needall v0.0.1