# This test illustrates a case where downgrading one module may upgrade another.
# Compare to the downcross2 test case in cmd/go/internal/mvs/mvs_test.go.

# The initial package import graph used in this test looks like:
#
# a ---- b ---- d
#
# The module dependency graph originally looks like:
#
# a ---- b.2 ---- d.2
#
# b.1 ---- c.1
#
# If we downgrade module d to version 1, we must downgrade b as well.
# If that downgrade selects b version 1, we will add a new dependency on module c.

cp go.mod go.mod.orig
go mod tidy
cmp go.mod.orig go.mod

go get example.com/d@v0.1.0
go list -m all
stdout '^example.com/b v0.1.0 '
stdout '^example.com/c v0.1.0 '
stdout '^example.com/d v0.1.0 '

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

go 1.15

require example.com/b v0.2.0

replace (
	example.com/b v0.1.0 => ./b1
	example.com/b v0.2.0 => ./b2
	example.com/c v0.1.0 => ./c
	example.com/d v0.1.0 => ./d
	example.com/d v0.2.0 => ./d
)
-- a.go --
package a

import _ "example.com/b"

-- b1/go.mod --
module example.com/b

go 1.15

require example.com/c v0.1.0
-- b1/b.go --
package b

import _ "example.com/c"

-- b2/go.mod --
module example.com/b

go 1.15

require example.com/d v0.2.0
-- b2/b.go --
package b

import _ "example.com/d"

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

go 1.15

-- c/c.go --
package c

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

go 1.15
-- d/d.go --
package d