1 files changed, 45 insertions, 0 deletions
diff --git a/libgo/go/cmd/go/testdata/script/mod_in_testdata_dir.txt b/libgo/go/cmd/go/testdata/script/mod_in_testdata_dir.txt
new file mode 100644
index 00000000000..f582569798b
--- /dev/null
+++ b/libgo/go/cmd/go/testdata/script/mod_in_testdata_dir.txt
@@ -0,0 +1,45 @@
+# Regression test for golang.org/issue/28481:
+# 'mod tidy' removed dependencies if the module root was
+# within a directory named 'testdata' or '_foo'.
+
+env GO111MODULE=on
+
+# A module should be allowed in a directory named testdata.
+cd $WORK/testdata
+go mod init testdata.tld/foo
+
+# Building a package within that module should resolve its dependencies.
+go build
+grep 'rsc.io/quote' go.mod
+
+# Tidying the module should preserve those dependencies.
+go mod tidy
+grep 'rsc.io/quote' go.mod
+
+[short] stop
+
+# Vendoring the module's dependencies should work too.
+go mod vendor
+exists vendor/rsc.io/quote
+
+# The same should work in directories with names starting with underscores.
+cd $WORK/_ignored
+go mod init testdata.tld/foo
+
+go build
+grep 'rsc.io/quote' go.mod
+
+go mod tidy
+grep 'rsc.io/quote' go.mod
+
+go mod vendor
+exists vendor/rsc.io/quote
+
+-- $WORK/testdata/main.go --
+package foo
+
+import _ "rsc.io/quote"
+-- $WORK/_ignored/main.go --
+package foo
+
+import _ "rsc.io/quote"