cmd/go/testdata/script: don't use network in mod_gonoproxy test

Create fake modules in the proxy that we intend to not fetch.

For #80243

Change-Id: Iad6a205039fa2cf512073d5f4870ce776a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/795907
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/go/testdata/mod/vcs-test.golang.org_git_proxyonly.git_v0.0.1.txt

diff --git a/src/cmd/go/testdata/mod/vcs-test.golang.org_git_proxyonly.git_v0.0.1.txt b/src/cmd/go/testdata/mod/vcs-test.golang.org_git_proxyonly.git_v0.0.1.txt
new file mode 100644
index 0000000..ce83076
--- /dev/null
+++ b/src/cmd/go/testdata/mod/vcs-test.golang.org_git_proxyonly.git_v0.0.1.txt
@@ -0,0 +1,8 @@
+This is a module that could exist in a vcstest git repo, but that doesn't.
+
+-- .mod --
+module vcs-test.golang.org/git/proxyonly.git
+-- .info --
+{"Version":"v0.0.1"}
+-- proxyonly.go --
+package proxyonly

src/cmd/go/testdata/mod/vcs-test.golang.org_git_tagtests.git_v0.1.0.txt

diff --git a/src/cmd/go/testdata/mod/vcs-test.golang.org_git_tagtests.git_v0.1.0.txt b/src/cmd/go/testdata/mod/vcs-test.golang.org_git_tagtests.git_v0.1.0.txt
new file mode 100644
index 0000000..043bad3
--- /dev/null
+++ b/src/cmd/go/testdata/mod/vcs-test.golang.org_git_tagtests.git_v0.1.0.txt
@@ -0,0 +1,9 @@
+There's a tagtests git repo, but add a proxy version, so we
+can test that it's not available in mod_gonoproxy.
+
+-- .mod --
+module vcs-test.golang.org/git/tagtests.git
+-- .info --
+{"Version":"v0.1.0"}
+-- tagtests.go --
+package tagtests

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

diff --git a/src/cmd/go/testdata/script/mod_gonoproxy.txt b/src/cmd/go/testdata/script/mod_gonoproxy.txt
index 94d03f2..d704c54 100644
--- a/src/cmd/go/testdata/script/mod_gonoproxy.txt
+++ b/src/cmd/go/testdata/script/mod_gonoproxy.txt
@@ -35,21 +35,24 @@
 ! go get golang.org/x/text
 stderr '^go: golang.org/x/text: module lookup disabled by GOPROXY=off$'
 
+[short] skip 'the rest of the test uses git'
+
 # GONOPROXY bypasses proxy
-[!net:rsc.io] skip
 [!git] skip
+env GOPROXY=$proxy
+env GOSUMDB=$sumdb
 env GOPRIVATE=none
-env GONOPROXY='*/fortune'
-! go get rsc.io/fortune # does not exist in real world, only on test proxy
+env GONOPROXY='*/git/proxyonly.git'
+! go get vcs-test.golang.org/git/proxyonly.git  # does not exist in vcstest, only on test proxy
 stderr 'git ls-remote'
 
-[!net:golang.org] skip
-env GOSUMDB=
+env GOSUMDB=off
 env GONOPROXY=
-env GOPRIVATE='*/x'
-go get golang.org/x/text
+env GOPRIVATE='*/git/tagtests.git'
+go get vcs-test.golang.org/git/tagtests.git
 go list -m all
-! stdout 'text.*v0.0.0-2017' # should not have the version from the proxy
+stdout '^vcs-test.golang.org/git/tagtests.git v0.2.2$'
+! stdout 'tagtests.git v0.1.0' # should not have the version from the proxy
 
 -- go.mod.orig --
 module m