Fix auto strlen and add tests

Author: techrah

src/pinyin_compare.c

@@ -44,7 +44,7 @@ int pinyin_compare(void* data, int l1, const void* s1, int l2, const void* s2) {
   u8_state_init(&state2);
 
   int _l1 = l1 < 0 ? strlen(s1) : l1;
-  int _l2 = l1 < 0 ? strlen(s2) : l2;
+  int _l2 = l2 < 0 ? strlen(s2) : l2;
 
   int hf1 = homonym_frequency(s1, &state1);
   int hf2 = homonym_frequency(s2, &state2);

tests/test_misc.cpp

@@ -57,3 +57,11 @@ TEST(TestMisc, TestUmlaut) {
   ASSERT_LT(_pinyin_compare("lǚ", "luguan"), 0);
   ASSERT_LT(_pinyin_compare("nǜ", "nuǎn"), 0);
 }
+
+TEST(TestMisc, TestAutoStrLen) {
+  ASSERT_LT(pinyin_compare(NULL, 4, "abcde", 5, "abcde"), 0);
+  ASSERT_GT(pinyin_compare(NULL, 5, "abcde", 4, "abcde"), 0);
+  ASSERT_EQ(pinyin_compare(NULL, 5, "abcde", -1, "abcde"), 0);
+  ASSERT_EQ(pinyin_compare(NULL, -1, "abcde", 5, "abcde"), 0);
+  ASSERT_EQ(pinyin_compare(NULL, -1, "abcde", -1, "abcde"), 0);
+}