fix string according to reviews

tests/StringTest.cpp

@@ -117,10 +117,6 @@ TEST_CASE("String")
 		String str2("Hello World");
 		str2.ToLower();
 		REQUIRE(str2 == "hello world");
-
-		String str3("Georg will save us all from our doom");
-		str3.FirstLettersUpper();
-		REQUIRE(str3 == "Georg Will Save Us All From Our Doom");
 	}
 
 	SECTION("Substring")
@@ -138,4 +134,94 @@ TEST_CASE("String")
 		String str2("42.42");
 		REQUIRE(str2.FromString<float>() == 42.42f);
 	}
+
+	SECTION("StartsWith")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.StartsWith("Hello"));
+		REQUIRE(!str1.StartsWith("World"));
+	}
+
+	SECTION("EndsWith")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.EndsWith("World"));
+		REQUIRE(!str1.EndsWith("Hello"));
+	}
+
+	SECTION("Contains")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.Contains("Hello"));
+		REQUIRE(str1.Contains("World"));
+		REQUIRE(!str1.Contains("Georg"));
+	}
+
+	SECTION("FindEndIndexOf")
+	{
+		String str1("Georg will save us all from our doom");
+		REQUIRE(str1.FindEndIndexOf("save") == 11);
+	}
+
+	SECTION("TrimFront")
+	{
+		String str1("  Hello World");
+		REQUIRE(str1.TrimFront() == "Hello World");
+	}
+
+	SECTION("TrimBack")
+	{
+		String str1("Hello World  ");
+		REQUIRE(str1.TrimBack() == "Hello World");
+	}
+
+	SECTION("Empty")
+	{
+		String str1;
+		REQUIRE(str1.Empty());
+		REQUIRE(!str1);
+
+		String str2("Hello World");
+		REQUIRE(!str2.Empty());
+		REQUIRE(!!str2);
+	}
+
+	SECTION("Size")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.Size() == 11);
+	}
+
+	SECTION("Capacity")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.Capacity() >= 11);
+	}
+
+	SECTION("CharCount")
+	{
+		String str1("Hello World");
+		REQUIRE(str1.CharCount() == 11);
+	}
+
+	SECTION("PopBack")
+	{
+		String str1("Hello World");
+		str1.PopBack();
+		REQUIRE(str1 == "Hello Worl");
+	}
+
+	SECTION("Clear")
+	{
+		String str1("Hello World");
+		str1.Clear();
+		REQUIRE(str1.Empty());
+	}
+
+	SECTION("ShrinkToFit")
+	{
+		String str1("Hello World");
+		str1.ShrinkToFit();
+		REQUIRE(str1.Capacity() == 15); // 11 + 4 null terminators due to sso
+	}
 }