1 files changed, 131 insertions, 0 deletions
diff --git a/src/cmd/go/testdata/script/mod_lazy_test_horizon.txt b/src/cmd/go/testdata/script/mod_lazy_test_horizon.txt
new file mode 100644
index 0000000000..9cdfad79f6
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_lazy_test_horizon.txt
@@ -0,0 +1,131 @@
+# This file demonstrates the effect of lazy loading on the selected
+# versions of test dependencies.
+
+# The package import graph used in this test looks like:
+#
+# m ---- a
+#  \     |
+#   \    a_test ---- b
+#    \               |
+#     x              b_test
+#     |                    \
+#     x_test -------------- c
+#
+# And the module dependency graph looks like:
+#
+# m -- a.1 -- b.1 -- c.2
+#  \
+#   x.1 ------------ c.1
+
+# Control case: in Go 1.15, the version of c imported by 'go test x' is the
+# version required by module b, even though b_test is not relevant to the main
+# module. (The main module imports a, and a_test imports b, but all of the
+# packages and tests in the main module can be built without b.)
+
+go list -m c
+stdout '^c v0.2.0 '
+
+[!short] go test -v x
+[!short] stdout ' c v0.2.0$'
+
+# With lazy loading, the go.mod requirements are the same,
+# but the irrelevant dependency on c v0.2.0 should be pruned out,
+# leaving only the relevant dependency on c v0.1.0.
+
+go mod edit -go=1.16
+go list -m c
+stdout '^c v0.2.0'  # TODO(#36460): v0.1.0
+
+[!short] go test -v x
+[!short] stdout ' c v0.2.0$'  # TODO(#36460): v0.1.0
+
+-- m.go --
+package m
+
+import (
+	_ "a"
+	_ "x"
+)
+-- go.mod --
+module m
+
+go 1.15
+
+require (
+	a v0.1.0
+	x v0.1.0
+)
+
+replace (
+	a v0.1.0 => ./a1
+	b v0.1.0 => ./b1
+	c v0.1.0 => ./c1
+	c v0.2.0 => ./c2
+	x v0.1.0 => ./x1
+)
+-- a1/go.mod --
+module a
+
+go 1.16
+
+require b v0.1.0
+-- a1/a.go --
+package a
+-- a1/a_test.go --
+package a_test
+
+import _ "b"
+-- b1/go.mod --
+module b
+
+go 1.16
+
+require c v0.2.0
+-- b1/b.go --
+package b
+-- b1/b_test.go --
+package b_test
+
+import (
+	"c"
+	"testing"
+)
+
+func TestCVersion(t *testing.T) {
+	t.Log(c.Version)
+}
+-- c1/go.mod --
+module c
+
+go 1.16
+-- c1/c.go --
+package c
+
+const Version = "v0.1.0"
+-- c2/go.mod --
+module c
+
+go 1.16
+-- c2/c.go --
+package c
+
+const Version = "v0.2.0"
+-- x1/go.mod --
+module x
+
+go 1.16
+
+require c v0.1.0
+-- x1/x.go --
+package x
+-- x1/x_test.go --
+package x_test
+
+import (
+	"c"
+	"testing"
+)
+
+func TestCVersion(t *testing.T) {
+	t.Log("c", c.Version)
+}