tests: add unit test for cjk handling

This test exposes some problem finding longer CJK strings; see: issue #1428.
The test does not _pass_ yet, so skip it for now.

mu/tests/test-mu-query.cc

@@ -559,6 +559,43 @@ test_mu_query_threads_compilation_error(void)
 	                 3);
 }
 
+/* https://github.com/djcb/mu/issues/1428 */
+static void
+test_mu_query_cjk(void)
+{
+	/* XXX: this doesn't pass yet; return for now */
+	g_test_skip("skip CJK tests");
+	return;
+
+	{
+		g_unsetenv("XAPIAN_CJK_NGRAM");
+		const auto xpath = make_database(MU_TESTMAILDIR_CJK);
+		g_assert_cmpuint(run_and_count_matches(xpath,
+						       "サーバがダウンしました",
+						       QueryFlags::None),
+				 ==, 1);
+		g_assert_cmpuint(run_and_count_matches(xpath,
+						       "サーバ",
+						       QueryFlags::None),
+				 ==, 0);
+	}
+
+
+	{
+		g_setenv("XAPIAN_CJK_NGRAM", "1", TRUE);
+		const auto xpath = make_database(MU_TESTMAILDIR_CJK);
+		g_assert_cmpuint(run_and_count_matches(xpath,
+						       "サーバがダウンしました",
+						       QueryFlags::None),
+				 ==, 0);
+		g_assert_cmpuint(run_and_count_matches(xpath,
+						       "サーバ",
+						       QueryFlags::None),
+				 ==, 0);
+	}
+}
+
+
 int
 main(int argc, char* argv[])
 {
@@ -608,6 +645,9 @@ main(int argc, char* argv[])
 	g_test_add_func("/mu-query/test-mu-query-threads-compilation-error",
 	                test_mu_query_threads_compilation_error);
 
+	g_test_add_func("/mu-query/test-mu-query-cjk",
+	                test_mu_query_cjk);
+
 	if (!g_test_verbose())
 		g_log_set_handler(NULL,
 		                  (GLogLevelFlags)(G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL |