Fix calling espeak_Synth without first setting a voice, with tests.

Makefile.am

@@ -245,6 +245,12 @@ tests_readclause_test_CFLAGS  = -Isrc/libespeak-ng ${AM_CFLAGS}
 tests_readclause_test_LDADD   = src/libespeak-ng-test.la
 tests_readclause_test_SOURCES = tests/readclause.c
 
+noinst_bin_PROGRAMS += tests/api.test
+
+tests_api_test_CFLAGS  = -Isrc/libespeak-ng ${AM_CFLAGS}
+tests_api_test_LDADD   = src/libespeak-ng-test.la
+tests_api_test_SOURCES = tests/api.c
+
 %.check: %.test
 	@echo "  TEST      $<"
 	@ESPEAK_DATA_PATH=$(PWD) $< && echo "  PASSED    $<"
@@ -252,6 +258,7 @@ tests_readclause_test_SOURCES = tests/readclause.c
 check:	tests/encoding.check \
 	tests/tokenizer.check \
 	tests/readclause.check \
+	tests/api.check \
 	tests/languages.check
 
 ##### phoneme data:

src/libespeak-ng/speech.c

@@ -399,7 +399,7 @@ static espeak_ng_STATUS Synthesize(unsigned int unique_identifier, const void *t
 	count_samples = 0;
 
 	if (translator == NULL)
-		espeak_SetVoiceByName("default");
+		espeak_SetVoiceByName("en");
 
 	if (p_decoder == NULL)
 		p_decoder = create_text_decoder();

tests/api.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2017 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write see:
+ *             <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <espeak-ng/espeak_ng.h>
+#include <espeak-ng/speak_lib.h>
+#include <espeak-ng/encoding.h>
+
+#include "speech.h"
+#include "phoneme.h"
+#include "synthesize.h"
+#include "translate.h"
+
+void
+test_espeak_terminate_without_initialize()
+{
+	printf("testing espeak_Terminate without espeak_Initialize\n");
+
+	assert(event_list == NULL);
+
+	assert(espeak_Terminate() == EE_OK);
+	assert(event_list == NULL);
+}
+
+void
+test_espeak_initialize()
+{
+	printf("testing espeak_Initialize\n");
+
+	assert(event_list == NULL);
+
+	assert(espeak_Initialize(AUDIO_OUTPUT_PLAYBACK, 0, NULL, 0) == 22050);
+	assert(event_list != NULL);
+
+	assert(espeak_Terminate() == EE_OK);
+	assert(event_list == NULL);
+}
+
+void
+test_espeak_synth()
+{
+	printf("testing espeak_Synth\n");
+
+	assert(event_list == NULL);
+
+	assert(espeak_Initialize(AUDIO_OUTPUT_RETRIEVAL, 0, NULL, 0) == 22050);
+	assert(event_list != NULL);
+
+	const char *test = "One two three.";
+	assert(espeak_Synth(test, strlen(test)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, NULL, NULL) == EE_OK);
+	assert(espeak_Synchronize() == EE_OK);
+
+	assert(espeak_Terminate() == EE_OK);
+	assert(event_list == NULL);
+}
+
+int
+main(int argc, char **argv)
+{
+	test_espeak_terminate_without_initialize();
+	test_espeak_initialize();
+
+	test_espeak_synth();
+
+	return EXIT_SUCCESS;
+}