vendor Catch2 and ETL

contrib/fsfw_contrib/Catch2-3.7.1/docs/tostring.md

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+# String conversions
+
+**Contents**<br>
+[operator << overload for std::ostream](#operator--overload-for-stdostream)<br>
+[Catch::StringMaker specialisation](#catchstringmaker-specialisation)<br>
+[Catch::is_range specialisation](#catchis_range-specialisation)<br>
+[Exceptions](#exceptions)<br>
+[Enums](#enums)<br>
+[Floating point precision](#floating-point-precision)<br>
+
+
+Catch needs to be able to convert types you use in assertions and logging expressions into strings (for logging and reporting purposes).
+Most built-in or std types are supported out of the box but there are two ways that you can tell Catch how to convert your own types (or other, third-party types) into strings.
+
+## operator << overload for std::ostream
+
+This is the standard way of providing string conversions in C++ - and the chances are you may already provide this for your own purposes. If you're not familiar with this idiom it involves writing a free function of the form:
+
+```cpp
+std::ostream& operator << ( std::ostream& os, T const& value ) {
+    os << convertMyTypeToString( value );
+    return os;
+}
+```
+
+(where ```T``` is your type and ```convertMyTypeToString``` is where you'll write whatever code is necessary to make your type printable - it doesn't have to be in another function).
+
+You should put this function in the same namespace as your type, or the global namespace, and have it declared before including Catch's header.
+
+## Catch::StringMaker specialisation
+If you don't want to provide an ```operator <<``` overload, or you want to convert your type differently for testing purposes, you can provide a specialization for `Catch::StringMaker<T>`:
+
+```cpp
+namespace Catch {
+    template<>
+    struct StringMaker<T> {
+        static std::string convert( T const& value ) {
+            return convertMyTypeToString( value );
+        }
+    };
+}
+```
+
+## Catch::is_range specialisation
+As a fallback, Catch attempts to detect if the type can be iterated
+(`begin(T)` and `end(T)` are valid) and if it can be, it is stringified
+as a range. For certain types this can lead to infinite recursion, so
+it can be disabled by specializing `Catch::is_range` like so:
+
+```cpp
+namespace Catch {
+    template<>
+    struct is_range<T> {
+        static const bool value = false;
+    };
+}
+
+```
+
+
+## Exceptions
+
+By default all exceptions deriving from `std::exception` will be translated to strings by calling the `what()` method. For exception types that do not derive from `std::exception` - or if `what()` does not return a suitable string - use `CATCH_TRANSLATE_EXCEPTION`. This defines a function that takes your exception type, by reference, and returns a string. It can appear anywhere in the code - it doesn't have to be in the same translation unit. For example:
+
+```cpp
+CATCH_TRANSLATE_EXCEPTION( MyType const& ex ) {
+    return ex.message();
+}
+```
+
+## Enums
+
+> Introduced in Catch2 2.8.0.
+
+Enums that already have a `<<` overload for `std::ostream` will convert to strings as expected.
+If you only need to convert enums to strings for test reporting purposes you can provide a `StringMaker` specialisations as any other type.
+However, as a convenience, Catch provides the `REGISTER_ENUM` helper macro that will generate the `StringMaker` specialisation for you with minimal code.
+Simply provide it the (qualified) enum name, followed by all the enum values, and you're done!
+
+E.g.
+
+```cpp
+enum class Fruits { Banana, Apple, Mango };
+
+CATCH_REGISTER_ENUM( Fruits, Fruits::Banana, Fruits::Apple, Fruits::Mango )
+
+TEST_CASE() {
+    REQUIRE( Fruits::Mango == Fruits::Apple );
+}
+```
+
+... or if the enum is in a namespace:
+```cpp
+namespace Bikeshed {
+    enum class Colours { Red, Green, Blue };
+}
+
+// Important!: This macro must appear at top level scope - not inside a namespace
+// You can fully qualify the names, or use a using if you prefer
+CATCH_REGISTER_ENUM( Bikeshed::Colours,
+    Bikeshed::Colours::Red,
+    Bikeshed::Colours::Green,
+    Bikeshed::Colours::Blue )
+
+TEST_CASE() {
+    REQUIRE( Bikeshed::Colours::Red == Bikeshed::Colours::Blue );
+}
+```
+
+## Floating point precision
+
+> [Introduced](https://github.com/catchorg/Catch2/issues/1614) in Catch2 2.8.0.
+
+Catch provides a built-in `StringMaker` specialization for both `float`
+and `double`. By default, it uses what we think is a reasonable precision,
+but you can customize it by modifying the `precision` static variable
+inside the `StringMaker` specialization, like so:
+
+```cpp
+        Catch::StringMaker<float>::precision = 15;
+        const float testFloat1 = 1.12345678901234567899f;
+        const float testFloat2 = 1.12345678991234567899f;
+        REQUIRE(testFloat1 == testFloat2);
+```
+
+This assertion will fail and print out the `testFloat1` and `testFloat2`
+to 15 decimal places.
+
+---
+
+[Home](Readme.md#top)