Function TestDDProxyFunc_BypassesLoopbackOnly

internal/desktop/proxy_test.go:135–170

TestDDProxyFunc_BypassesLoopbackOnly exercises the proxy selection directly (rather than through ProxyTransport, which needs a live socket) so it runs on every platform, including Windows. This is the core of the docker/compose#13824 fix: loopback targets must connect directly instead of being force

(t *testing.T)

// proxy, so Desktop keeps ownership of proxy decisions (docker/compose#13825
// review).
func TestDDProxyFunc_BypassesLoopbackOnly(t *testing.T) {
	// Set NO_PROXY to confirm it is deliberately NOT honored: registry.internal
	// must still be proxied.
	t.Setenv("NO_PROXY", "registry.internal")
	t.Setenv("no_proxy", "registry.internal")

	proxyFunc := ddProxyFunc()

	cases := []struct {
		name      string
		reqURL    string
		wantProxy bool
	}{
		{"loopback name", "http://localhost:5000/v2/", false},
		{"loopback IPv4", "http://127.0.0.1:5000/v2/", false},
		{"loopback IPv4 subnet", "http://127.5.6.7:5000/v2/", false},
		{"loopback IPv6", "http://[::1]:5000/v2/", false},
		{"NO_PROXY host is not honored", "https://registry.internal/v2/", true},
		{"external https", "https://registry-1.docker.io/v2/", true},
		{"external http", "http://example.com/v2/", true},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			req, err := http.NewRequest(http.MethodGet, tc.reqURL, http.NoBody)
			assert.NilError(t, err)
			proxyURL, err := proxyFunc(req)
			assert.NilError(t, err)
			if tc.wantProxy {
				assert.Assert(t, proxyURL != nil, "expected %s to route through the Docker Desktop proxy", tc.reqURL)
				assert.Equal(t, proxyURL.Host, ddProxyHost)
			} else {
				assert.Assert(t, proxyURL == nil, "expected %s to bypass the proxy and connect directly", tc.reqURL)
			}
		})
	}
}

func mustTouch(t *testing.T, path string) {
	t.Helper()