add test cases and allow to clear an error state

Signed-off-by: Denys Smirnov <denys@sourced.tech>

src/libuast.hpp

@@ -642,10 +642,13 @@ namespace uast {
             UastSourceIndexFree(idx);
             idx = nullptr;
         }
-        // CheckError throws a last encountered error, if any.
+        // CheckError throws a last encountered error, if any, and clear the error state of an index.
         void CheckError() {
             char* err = UastSourceIndex_LastError(idx);
-            if (err) throw std::runtime_error(err);
+            if (err) {
+                UastSourceIndex_ClearError(idx);
+                throw std::runtime_error(err);
+            }
         }
         // FromLineCol converts one-based line-column pair (in bytes) in the indexed
         // source file to a zero-based byte offset. It return -1 in case of failure.

src/src_index.go

@@ -90,6 +90,14 @@ func UastSourceIndex_LastError(idx *C.UastSourceIndex) *C.char {
 	return C.CString(err.Error())
 }
 
+//export UastSourceIndex_ClearError
+// UastSourceIndex_ClearError clears an error state.
+func UastSourceIndex_ClearError(idx *C.UastSourceIndex) {
+	if index := getSourceIndexFrom(idx); index != nil {
+		index.setError(nil)
+	}
+}
+
 // getSourceIndexFrom returns an index for a given C.UastSourceIndex pointer. It returns nil if C structure is invalid.
 func getSourceIndexFrom(idx *C.UastSourceIndex) *sourceIndex {
 	if idx == nil || idx.handle == 0 {

tests/main.cc

@@ -5,6 +5,7 @@ extern "C" {
 
 #include "nodes_test.h"
 #include "roles_test.h"
+#include "src_index_test.h"
 
 #define ADD_TEST(__SUITE__, __MESSAGE__, __FUNC__)             \
   if (CU_add_test(__SUITE__, __MESSAGE__, __FUNC__) == NULL) { \
@@ -95,6 +96,7 @@ int main() {
   ADD_TEST(suite, "test of UastFilter() with bad query", TestUastFilterBadQuery);
   ADD_TEST(suite, "test failing UastFilter() (bad Xpath)", TestXpath);
   ADD_TEST(suite, "test empty UastFilter() result", TestEmptyResult);
+  ADD_TEST(suite, "test source index", TestSourceIndex);
 
   // run all tests using the CUnit Basic interface
   CU_basic_set_mode(CU_BRM_VERBOSE);

tests/src_index_test.h

@@ -0,0 +1,44 @@
+#ifndef LIBUAST_SRC_INDEX_TEST_H_
+#define LIBUAST_SRC_INDEX_TEST_H_
+
+#include <cstdio>
+#include <cstring>
+
+extern "C" {
+#include <CUnit/Basic.h>
+}
+
+#include "libuast.h"
+
+static void TestSourceIndex(void) {
+  const char src[] = "tёst\ndata\n";
+  UastSourceIndex *idx = UastSourceIndexNew((void*)src, sizeof(src));
+  CU_ASSERT_FATAL(idx != NULL);
+
+  // Conversions to different offsets
+  CU_ASSERT_EQUAL_FATAL(UastSourceIndex_FromUnicode(idx, 0), 0);
+  CU_ASSERT_EQUAL_FATAL(UastSourceIndex_FromUnicode(idx, 2), 3);
+  CU_ASSERT_EQUAL_FATAL(UastSourceIndex_FromLineCol(idx, 2, 1), 6);
+
+  // Conversion to line-column
+  UastLineCol lc = UastSourceIndex_ToLineCol(idx, 8);
+  CU_ASSERT_EQUAL_FATAL(lc.line, 2);
+  CU_ASSERT_EQUAL_FATAL(lc.col, 3);
+
+  // There should be no error this far
+  CU_ASSERT_FATAL(UastSourceIndex_LastError(idx) == NULL);
+
+  // Invalid offset should lead to -1
+  CU_ASSERT_EQUAL_FATAL(UastSourceIndex_ToUnicode(idx, sizeof(src)+1), -1);
+  char* err = UastSourceIndex_LastError(idx);
+  CU_ASSERT_FATAL(err != NULL);
+  delete(err);
+
+  // Clear error state
+  UastSourceIndex_ClearError(idx);
+  CU_ASSERT_FATAL(UastSourceIndex_LastError(idx) == NULL);
+
+  UastSourceIndexFree(idx);
+}
+
+#endif  // LIBUAST_SRC_INDEX_TEST_H_