tests: clean up tests

- Move all module tests to their own directories.

- Avoid duplication of `// import`.

tests/modules/programs/getmail/default.nix

@@ -0,0 +1,3 @@
+{
+  getmail = ./getmail.nix;
+}

tests/modules/programs/getmail/getmail-expected.conf

@@ -0,0 +1,16 @@
+# Generated by Home-Manager.
+[retriever]
+type = SimpleIMAPSSLRetriever
+server = imap.example.com
+port = 993
+username = home.manager
+password_command = ('password-command')
+mailboxes = ( 'INBOX', 'Sent', 'Work' )
+
+[destination]
+type = MDA_external
+path = /bin/maildrop
+
+[options]
+delete = false
+read_all = true

tests/modules/programs/getmail/getmail.nix

@@ -0,0 +1,29 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  imports = [ ../../accounts/email-test-accounts.nix ];
+
+  config = {
+    home.username = "hm-user";
+    home.homeDirectory = "/home/hm-user";
+
+    accounts.email.accounts = {
+      "hm@example.com" = {
+        getmail = {
+          enable = true;
+          mailboxes = ["INBOX" "Sent" "Work"];
+          destinationCommand = "/bin/maildrop";
+          delete = false;
+        };
+        imap.port = 993;
+      };
+    };
+
+    nmt.script = ''
+      assertFileExists home-files/.getmail/getmailhm@example.com
+      assertFileContent home-files/.getmail/getmailhm@example.com ${./getmail-expected.conf}
+    '';
+  };
+}