Increasing coverage for library resolver

Author: cmaglie

Diff for: arduino/libraries/librariesresolver/cpp.go

@@ -151,10 +151,12 @@ func findLibraryWithNameBestDistance(name string, libs libraries.List) *librarie
 	closestName := cm.Closest(name)
 
 	// Return the closest-matching lib
+	var winner *libraries.Library
 	for _, lib := range libs {
 		if closestName == simplify(lib.Name) {
-			return lib
+			winner = lib
+			break
 		}
 	}
-	return nil
+	return winner
 }

Diff for: arduino/libraries/librariesresolver/cpp_test.go

@@ -48,6 +48,14 @@ func TestCppHeaderPriority(t *testing.T) {
 	require.True(t, r6 == r7)
 }
 
+func TestCppHeaderResolverWithNilResult(t *testing.T) {
+	resolver := NewCppResolver()
+	libraryList := libraries.List{}
+	libraryList.Add(l1)
+	resolver.headers["aaa.h"] = libraryList
+	require.Nil(t, resolver.ResolveFor("bbb.h", "avr"))
+}
+
 func TestCppHeaderResolver(t *testing.T) {
 	resolve := func(header string, libs ...*libraries.Library) string {
 		resolver := NewCppResolver()