# This file demonstrates the go.mod changes needed to ensure reproducibility
# when running 'go test' on a sequence of packages for which each package in the
# sequence is a test-only dependency of the previous package, as a user might do
# if they encounter a test failure while fixing a bug found in one of their
# dependencies.

cp go.mod go.mod.old
cp lazy.go lazy.go.old
go mod tidy
cmp go.mod go.mod.old

# Before adding a new import, the go.mod file should
# enumerate modules for all packages already imported.
go list -m all
stdout '^example.com/d v0.1.0' # not v0.2.0 as would be resolved by 'latest'
cp stdout list.old
cmp go.mod go.mod.old

# Following the chain of dependencies by listing test dependencies
# or running tests should not change the go.mod file.
go list -test -deps example.com/a
stdout '^example.com/a'
stdout '^example.com/b'
! stdout '^example.com/c'
[!short] go test -c example.com/a
cmp go.mod go.mod.old

go list -test -deps example.com/b
stdout '^example.com/b'
stdout '^example.com/c'
! stdout '^example.com/d'
[!short] go test -c example.com/b
cmp go.mod go.mod.old

go list -test -deps example.com/c
stdout '^example.com/c'
stdout '^example.com/d'
[!short] go test -c example.com/c
cmp go.mod go.mod.old

# When we add a new import of a package already imported by a test of a test of
# a dependency, and that dependency is already tidy, its transitive dependencies
# should already be present.
cp lazy.go.new lazy.go
go list all
go list -m all
cmp stdout list.old
cmp go.mod go.mod.new  # Indirect dependency promoted to direct.

# TODO(#36460):

cp lazy.go.old lazy.go
cp go.mod.old go.mod
go mod edit -go=1.16

# If we reach d by running successive tests, we should end up with exactly the
# version required by c, with an update to the go.mod file as soon as we load a
# dependency not found in the deepening scan.

# However, if we skip directly to adding a new import of d, the dependency is
# too far away for a deepening scan to find, which is fine because the package
# whose test imported it wasn't even in "all". It should resolve from the latest
# version of its module.

-- go.mod --
module example.com/lazy

go 1.14

require example.com/a v0.1.0

replace (
	example.com/a v0.1.0 => ./a
	example.com/b v0.1.0 => ./b
	example.com/c v0.1.0 => ./c
	example.com/d v0.1.0 => ./d1
	example.com/d v0.2.0 => ./d2
)
-- go.mod.new --
module example.com/lazy

go 1.14

require (
	example.com/a v0.1.0
	example.com/d v0.1.0
)

replace (
	example.com/a v0.1.0 => ./a
	example.com/b v0.1.0 => ./b
	example.com/c v0.1.0 => ./c
	example.com/d v0.1.0 => ./d1
	example.com/d v0.2.0 => ./d2
)
-- lazy.go --
package lazy

import (
	_ "example.com/a"
)

func main() {}
-- lazy.go.new --
package lazy

import (
	_ "example.com/a"
	"example.com/d"
)

func main() {
	println(d.Version)
}
-- a/go.mod --
module example.com/a

go 1.14

require example.com/b v0.1.0
-- a/a.go --
package a
import _ "example.com/b"
-- b/go.mod --
module example.com/b

go 1.16

require example.com/c v0.1.0
-- b/b.go --
package b
-- b/b_test.go --
package b
import _ "example.com/c"
-- c/go.mod --
module example.com/c

go 1.16

require example.com/d v0.1.0
-- c/c.go --
package c
-- c/c_test.go --
package c
import _ "example.com/d"
-- d1/go.mod --
module example.com/d

go 1.16
-- d1/d.go --
package d
const Version = "v0.1.0"
-- d2/go.mod --
module example.com/d

go 1.16
-- d2/d.go --
package d
const Version = "v0.2.0"