tools: use VPM_NO_INCREMENT env var to skip dl count increment when…

… testing vpm (#19756)

cmd/tools/vpm/common.v

@@ -239,6 +239,10 @@ fn ensure_vcs_is_installed(vcs &VCS) ! {
 }
 
 fn increment_module_download_count(name string) ! {
+	if no_dl_count_increment {
+		println('Skipping download count increment for "${name}".')
+		return
+	}
 	mut errors := []string{}
 
 	for server_url in vpm_server_urls {

cmd/tools/vpm/install_test.v

@@ -10,6 +10,7 @@ const (
 
 fn testsuite_begin() {
 	os.setenv('VMODULES', test_path, true)
+	os.setenv('VPM_NO_INCREMENT', '1', true)
 }
 
 fn testsuite_end() {
@@ -19,6 +20,7 @@ fn testsuite_end() {
 fn test_install_from_vpm_ident() {
 	res := os.execute('${v} install nedpals.args')
 	assert res.exit_code == 0, res.output
+	assert res.output.contains('Skipping download count increment for "nedpals.args".')
 	mod := vmod.from_file(os.join_path(test_path, 'nedpals', 'args', 'v.mod')) or {
 		assert false, err.str()
 		return

cmd/tools/vpm/vpm.v

@@ -27,6 +27,7 @@ struct VCS {
 
 const (
 	settings                = &VpmSettings{}
+	no_dl_count_increment   = os.getenv('VPM_NO_INCREMENT') == '1'
 	default_vpm_server_urls = ['https://vpm.vlang.io', 'https://vpm.url4e.com']
 	vpm_server_urls         = rand.shuffle_clone(default_vpm_server_urls) or { [] } // ensure that all queries are distributed fairly
 	valid_vpm_commands      = ['help', 'search', 'install', 'update', 'upgrade', 'outdated', 'list',