Rename isStdout => isConsole and add doccomment

src/catch2/internal/catch_console_colour.cpp

@@ -97,7 +97,7 @@ namespace {
             // Win32 text colour APIs can only be used on console streams
             // We cannot check that the output hasn't been redirected,
             // so we just check that the original stream is console stream.
-            return stream.isStdout();
+            return stream.isConsole();
         }
 
     private:
@@ -164,7 +164,7 @@ namespace {
             // only want to use the colours if we are writing to console.
             // However, console might be redirected, so we make an attempt at
             // checking for that on platforms where we know how to do that.
-            bool useColour = stream.isStdout();
+            bool useColour = stream.isConsole();
 #if defined( CATCH_INTERNAL_HAS_ISATTY ) && \
     !( defined( __DJGPP__ ) && defined( __STRICT_ANSI__ ) )
             ErrnoGuard _; // for isatty

src/catch2/internal/catch_stream.cpp

@@ -99,7 +99,7 @@ namespace Detail {
 
         public: // IStream
             std::ostream& stream() const override { return m_os; }
-            bool isStdout() const override { return true; }
+            bool isConsole() const override { return true; }
         };
 
         class CerrStream : public IStream {
@@ -113,7 +113,7 @@ namespace Detail {
 
         public: // IStream
             std::ostream& stream() const override { return m_os; }
-            bool isStdout() const override { return true; }
+            bool isConsole() const override { return true; }
         };
 
         ///////////////////////////////////////////////////////////////////////////

src/catch2/internal/catch_stream.hpp

@@ -26,9 +26,18 @@ namespace Catch {
     public:
         virtual ~IStream(); // = default
         virtual std::ostream& stream() const = 0;
-        // Win32 colour supports requires us to identify whether a stream
-        // is backed by stdout (so we can colour it) or not (and we can't).
-        virtual bool isStdout() const { return false;  }
+        /**
+         * Best guess on whether the instance is writing to a console (e.g. via stdout/stderr)
+         *
+         * This is useful for e.g. Win32 colour support, because the Win32
+         * API manipulates console directly, unlike POSIX escape codes,
+         * that can be written anywhere.
+         *
+         * Due to variety of ways to change where the stdout/stderr is
+         * _actually_ being written, users should always assume that
+         * the answer might be wrong.
+         */
+        virtual bool isConsole() const { return false; }
     };
 
     auto makeStream( std::string const& filename ) -> Detail::unique_ptr<IStream const>;