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

# This file demonstrates the effect of lazy loading on the reproducibility of
# tests (and tests of test dependencies) outside the main module.
#
# It is similar to the cases in mod_all.txt and mod_lazy_test_horizon.txt, but
# focuses on the effect of "go test" on specific packages instead of the "all"
# pattern.

# The package import graph used in this test looks like:
#
# lazy ---- a
#           |
#           a_test ---- b
#                       |
#                       b_test ---- c
#
# And the non-lazy module dependency graph looks like:
#
# lazy ---- a.1 ---- b.1 ---- c.1

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

# In Go 1.15 mode, 'go list -m all' includes modules needed by the
# transitive closure of tests of dependencies of tests of dependencies of ….

go list -m all
stdout 'example.com/b v0.1.0'
stdout 'example.com/c v0.1.0'
cmp go.mod go.mod.old

# 'go test' (or equivalent) of any such dependency, no matter how remote, does
# not update the go.mod file.

go list -test -deps example.com/a
stdout example.com/b
! stdout example.com/c

[!short] go test -c example.com/a
[!short] cmp go.mod go.mod.old

go list -test -deps example.com/b
stdout example.com/c

[!short] go test -c example.com/b
[!short] cmp go.mod go.mod.old

# TODO(#36460):

# After changing to 'go 1.16` uniformly, 'go list -m all' should prune out
# example.com/c, because it is not imported by any package (or test of a package)
# transitively imported by the main module.
#
# example.com/a is imported,
# and example.com/b is needed in order to run 'go test example.com/a',
# but example.com/c is not needed because we don't expect the user to need to run
# 'go test example.com/b'.

# If we skip directly to adding a new import of c, 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 it "all". It should resolve from the latest
# version of its module.

# However, if we reach c by running successive tests starting from the main
# module, we should end up with exactly the version require by c, with an update
# to the go.mod file as soon as we test a test dependency that is not itself in
# "all".

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

go 1.15

require example.com/a v0.1.0

replace (
	example.com/a v0.1.0 => ./a
	example.com/b v0.1.0 => ./b1
	example.com/b v0.2.0 => ./b2
	example.com/c v0.1.0 => ./c1
	example.com/c v0.2.0 => ./c2
)
-- lazy.go --
package lazy

import (
	_ "example.com/a"
)
-- a/go.mod --
module example.com/a

go 1.15

require example.com/b v0.1.0
-- a/a.go --
package a
-- a/a_test.go --
package a

import (
	"testing"

	_ "example.com/b"
)

func TestUsingB(t *testing.T) {
	// …
}
-- b1/go.mod --
module example.com/b

go 1.15

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

import _ "example.com/c"
-- b2/go.mod --
module example.com/b

go 1.15

require example.com/c v0.1.0
-- b2/b.go --
package b
This file should not be used, so this syntax error should be ignored.
-- b2/b_test.go --
package b
This file should not be used, so this syntax error should be ignored.
-- c1/go.mod --
module example.com/c

go 1.15
-- c1/c.go --
package c
-- c2/go.mod --
module example.com/c

go 1.15
-- c2/c.go --
package c
This file should not be used, so this syntax error should be ignored.