betterbird: lock the ask to be the default mail client off, so it never shows at a start (hq issue 345)

Betterbird's own default asks at every start with a window to become the default for mail, news, feeds and
calendar files. The policy locks mail.shell.checkDefaultClient off, which wins over a profile's own value, and
betterbird_check says when a node would still ask.

modules/betterbird/cmd/betterbird-tools/install_test.go

@@ -172,3 +172,60 @@ func TestTheUserJSDescriptionSaysAdoption(t *testing.T) {
 		}
 	}
 }
+
+// Betterbird never asks at its start to be the default mail client: the module's policy locks
+// mail.shell.checkDefaultClient off, and the check says so when it is on (novox/hq issue 345).
+func TestTheDefaultClientAskIsLockedOffAndTheCheckSaysWhenItIsOn(t *testing.T) {
+	f := newFake(t)
+	f.betterbird()
+	f.placedByTheMesh()
+	links(t, nil)
+	asks := func() string {
+		t.Helper()
+		c, err := f.Check()
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, x := range c.Findings {
+			if strings.Contains(x.What, "asks at its start") {
+				return x.What + " | " + x.Do
+			}
+		}
+		return ""
+	}
+	if got := asks(); got != "" {
+		t.Fatalf("the module's policy locks the ask off, yet: %s", got)
+	}
+	unlocked := `{"policies": {"DisableAppUpdate": true, "ExtensionSettings": {"owl@beonex.com": {"installation_mode": "force_installed",
+	  "install_url": "file:///opt/betterbird/owl/owl.xpi", "updates_disabled": true}}}}`
+	if why := policyProblem([]byte(unlocked)); !strings.Contains(why, defaultClientPref) {
+		t.Fatalf("a policy that leaves the ask on is said: %q", why)
+	}
+	f.write(policyFile, unlocked)
+	if got := asks(); !strings.Contains(got, "default mail client") || !strings.Contains(got, "push the module") {
+		t.Fatalf("the ask on is a finding with its remedy: %q", got)
+	}
+	f.write(policyFile, `{"policies": {"DisableAppUpdate": true, "Preferences": {"mail.shell.checkDefaultClient": {"Value": false, "Status": "default"}},
+	  "ExtensionSettings": {"owl@beonex.com": {"installation_mode": "force_installed", "install_url": "file:///opt/betterbird/owl/owl.xpi", "updates_disabled": true}}}}`)
+	if why := policyProblem(mustRead(t, f, policyFile)); !strings.Contains(why, "locked") {
+		t.Fatalf("a default the profile can override is not a lock: %q", why)
+	}
+	f.write(profileDir+"/prefs.js", `user_pref("mail.shell.checkDefaultClient", true);`+"\n")
+	if got := asks(); got == "" {
+		t.Fatal("a profile that turned the ask back on over an unlocked default is a finding")
+	}
+	f.write(policyFile, unlocked)
+	f.write(profileDir+"/prefs.js", `user_pref("mail.shell.checkDefaultClient", false);`+"\n")
+	if got := asks(); got != "" {
+		t.Fatalf("a profile with the ask off does not ask: %s", got)
+	}
+}
+
+func mustRead(t *testing.T, f *fake, p string) []byte {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join(f.Root, p))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return raw
+}