added config for virtual phone number

internal/app/help/service_email_signup_test.go

@@ -0,0 +1,59 @@
+package help
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+)
+
+// TestAppConfigEmailSignupPhonePrefixes asserts email_signup_phone_prefixes
+// is only present alongside email_signup_enabled=true, carries exactly the
+// configured prefix list, and that changing the list bumps the hash so
+// clients don't cache a stale list.
+func TestAppConfigEmailSignupPhonePrefixes(t *testing.T) {
+	ctx := context.Background()
+
+	disabled := NewService(nil, nil)
+	cfg, _, err := disabled.GetAppConfig(ctx, 0)
+	if err != nil {
+		t.Fatalf("GetAppConfig (disabled): %v", err)
+	}
+	var decoded map[string]any
+	if err := json.Unmarshal(cfg.JSON, &decoded); err != nil {
+		t.Fatalf("app config json invalid: %v", err)
+	}
+	if _, present := decoded["email_signup_phone_prefixes"]; present {
+		t.Fatalf("email_signup_phone_prefixes present while email signup disabled: %+v", decoded["email_signup_phone_prefixes"])
+	}
+
+	enabled := NewService(nil, nil,
+		WithEmailSignupEnable(true),
+		WithEmailSignupPhonePrefixes([]string{"888", "380", "373"}))
+	cfg2, _, err := enabled.GetAppConfig(ctx, 0)
+	if err != nil {
+		t.Fatalf("GetAppConfig (enabled): %v", err)
+	}
+	if err := json.Unmarshal(cfg2.JSON, &decoded); err != nil {
+		t.Fatalf("app config json invalid: %v", err)
+	}
+	rawPrefixes, ok := decoded["email_signup_phone_prefixes"].([]any)
+	if !ok || len(rawPrefixes) != 3 {
+		t.Fatalf("email_signup_phone_prefixes = %+v, want [888 380 373]", decoded["email_signup_phone_prefixes"])
+	}
+	for i, want := range []string{"888", "380", "373"} {
+		if rawPrefixes[i] != want {
+			t.Fatalf("email_signup_phone_prefixes[%d] = %v, want %q", i, rawPrefixes[i], want)
+		}
+	}
+
+	other := NewService(nil, nil,
+		WithEmailSignupEnable(true),
+		WithEmailSignupPhonePrefixes([]string{"888"}))
+	cfg3, _, err := other.GetAppConfig(ctx, 0)
+	if err != nil {
+		t.Fatalf("GetAppConfig (different prefixes): %v", err)
+	}
+	if cfg3.Hash == cfg2.Hash {
+		t.Fatalf("hash unchanged (%d) despite a different prefix list, clients would stay cached on the old list", cfg3.Hash)
+	}
+}