test: add Emacs notmuch-hello tests for custom tags and queries section.

The tests use default values from customization widgets to make sure
that these customization widgets work (at least on basic level).

The custom queries section test is currently broken.

test/emacs-hello

@@ -44,6 +44,21 @@ test_emacs "(let ((notmuch-hello-sections
              (test-output))"
 test_expect_equal_file OUTPUT $EXPECTED/notmuch-hello-section-counts
 
+test_begin_subtest "Empty custom tags section"
+test_emacs "(let* ((widget (widget-create 'notmuch-hello-tags-section))
+                   (notmuch-hello-sections (list (widget-value widget))))
+             (notmuch-hello)
+             (test-output))"
+test_expect_equal_file OUTPUT $EXPECTED/notmuch-hello-empty-custom-tags-section
+
+test_begin_subtest "Empty custom queries section"
+test_subtest_known_broken
+test_emacs "(let* ((widget (widget-create 'notmuch-hello-query-section))
+                   (notmuch-hello-sections (list (widget-value widget))))
+             (notmuch-hello)
+             (test-output))"
+test_expect_equal_file OUTPUT $EXPECTED/notmuch-hello-empty-custom-queries-section
+
 test_begin_subtest "Column alignment for tag/queries with long names"
 tag=a-very-long-tag # length carefully calculated for 80 characters window width
 notmuch tag +$tag '*'

test/emacs.expected-output/notmuch-hello-empty-custom-queries-section

@@ -0,0 +1,3 @@
+: [hide]
+
+

test/emacs.expected-output/notmuch-hello-empty-custom-tags-section

@@ -0,0 +1,5 @@
+: [hide]
+
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+