cmd/govim: put install scripts tests behind env var (govim#632)

Currently we skip long-running tests when running go test with -short.
This is standard practice. But as part of efforts to add the govim test
suite to the gopls integration tests:

https://go-review.googlesource.com/c/tools/+/212018

we now need to distinguish between all long running tests and those long
running tests that are install/network related.

Hence we now only run install script tests when
GOVIM_RUN_INSTALL_TESTSCRIPTS=true.

Fixes govim#631

_scripts/dockerRun.sh

@@ -36,6 +36,9 @@ go install golang.org/x/tools/gopls
 # remove all generated files to ensure we are never stale
 rm -f $(git ls-files -- ':!:cmd/govim/internal/golang_org_x_tools' '**/gen_*.*' 'gen_*.*') .travis.yml
 
+# run the install scripts
+export GOVIM_RUN_INSTALL_TESTSCRIPTS=true
+
 go generate $(go list ./... | grep -v 'govim/internal/golang_org_x_tools')
 go test $(go list ./... | grep -v 'govim/internal/golang_org_x_tools')
 

cmd/govim/main_test.go

@@ -26,6 +26,10 @@ import (
 	"github.com/rogpeppe/go-internal/testscript"
 )
 
+const (
+	EnvInstallScripts = "GOVIM_RUN_INSTALL_TESTSCRIPTS"
+)
+
 var (
 	fDebugLog  = flag.Bool("debugLog", false, "Whether to log debugging info from vim, govim and the test shim")
 	fGoplsPath = flag.String("gopls", "", "Path to the gopls binary for use in scenario tests. If unset, gopls is built from a tagged version.")
@@ -199,8 +203,8 @@ func TestScripts(t *testing.T) {
 }
 
 func TestInstallScripts(t *testing.T) {
-	if testing.Short() {
-		t.Skip("Install scripts are long-running")
+	if os.Getenv(EnvInstallScripts) != "true" {
+		t.Skipf("Skipping install scripts; %v != true", EnvInstallScripts)
 	}
 
 	govimPath := strings.TrimSpace(runCmd(t, "go", "list", "-m", "-f={{.Dir}}"))