add some tests for nfc_string (only UTF8 for now, UTF16 is TODO).

test/unittest_nfcstring.cc

@@ -0,0 +1,61 @@
+#include <gtest/gtest.h>
+
+#include "../src/nfc.hh"   // for illegal_utf8 exception
+#include <vector>
+
+using namespace pEp;
+using std::string_view;
+
+namespace {
+
+struct TestEntry
+{
+	string_view input;
+	string_view nfc;
+};
+
+typedef TestEntry TE;
+
+
+std::ostream& operator<<(std::ostream& o, const TestEntry& tt)
+{
+	return o << "input=«" << tt.input << "», nfc=«" << tt.nfc << "» ";
+}
+
+} // end of anonymous namespace
+
+
+TEST( NfcTestString, Simple )
+{
+	pEp::nfc_string s;
+	EXPECT_TRUE( s.empty() );
+	EXPECT_EQ( s.size(), 0 );
+	
+	s.reserve(1000);
+	EXPECT_GE(s.capacity(), 1000);
+	
+	s = "Ha\u0308user"; // non-NFC input will be normalized.
+	EXPECT_NE( s.get(), std::string("Ha\u0308user") );
+	EXPECT_EQ( s.get(), std::string("Häuser") );
+	
+	s.insert(0, "U\u0308ber");
+	EXPECT_EQ( s.get(), std::string("ÜberHäuser") );
+	
+	s += "\u0328\u030c"; // COMBINING OGONEK (below), COMBINING CARON (above)
+	// r absorbs the caron into U+0159, the combining ogonek remains separate
+	EXPECT_EQ( s.get(), std::string("ÜberHäuse\u0159\u0328") );
+	EXPECT_EQ( s.size(), 15);
+	
+	EXPECT_THROW( s.substr(1), pEp::illegal_utf );
+	EXPECT_THROW( s.substr(2, 10), pEp::illegal_utf );
+	
+	// removal of the r-with-caron let the remaining ogonek combine with the e to U+0119 (E WITH OGONEK)
+	EXPECT_EQ( s.erase(11, 2).get(), "ÜberHäus\u0119" );
+}
+
+
+TEST( NfcTestString, Exceptions )
+{
+	pEp::nfc_string s;
+	EXPECT_THROW( s = "Meep\xc0\x80.", pEp::illegal_utf );
+}