Add --force-colour option to force colour output.

Adding a --force-colour option to force colour output on POSIX systems,
provided a debugger is not attached.

This allows for Catch to output colours even if STDOUT is not a tty,
which can be the case when the test executable is being spawned by a
parent process (e.g. CMake's ctest).

include/internal/catch_commandline.hpp

@@ -170,6 +170,10 @@ namespace Catch {
             .describe( "set a specific seed for random numbers" )
             .bind( &setRngSeed, "'time'|number" );
 
+        cli["--force-colour"]
+            .describe( "force colourised output" )
+            .bind( &ConfigData::forceColour );
+
         return cli;
     }
 

include/internal/catch_config.hpp

@@ -37,6 +37,7 @@ namespace Catch {
             noThrow( false ),
             showHelp( false ),
             showInvisibles( false ),
+            forceColour( false ),
             abortAfter( -1 ),
             rngSeed( 0 ),
             verbosity( Verbosity::Normal ),
@@ -55,6 +56,7 @@ namespace Catch {
         bool noThrow;
         bool showHelp;
         bool showInvisibles;
+        bool forceColour;
 
         int abortAfter;
         unsigned int rngSeed;
@@ -131,7 +133,6 @@ namespace Catch {
 
         std::string getReporterName() const { return m_data.reporterName; }
 
-
         int abortAfter() const { return m_data.abortAfter; }
 
         TestSpec const& testSpec() const { return m_testSpec; }
@@ -148,6 +149,7 @@ namespace Catch {
         virtual ShowDurations::OrNot showDurations() const { return m_data.showDurations; }
         virtual RunTests::InWhatOrder runOrder() const  { return m_data.runOrder; }
         virtual unsigned int rngSeed() const    { return m_data.rngSeed; }
+        virtual bool forceColour() const { return m_data.forceColour; }
 
     private:
         ConfigData m_data;

include/internal/catch_console_colour_impl.hpp

@@ -143,7 +143,8 @@ namespace {
     };
 
     IColourImpl* platformColourInstance() {
-        return isatty(STDOUT_FILENO)
+        Ptr<IConfig const> config = getCurrentContext().getConfig();
+        return (config && config->forceColour()) || isatty(STDOUT_FILENO)
             ? PosixColourImpl::instance()
             : NoColourImpl::instance();
     }

include/internal/catch_interfaces_config.h

@@ -56,6 +56,7 @@ namespace Catch {
         virtual TestSpec const& testSpec() const = 0;
         virtual RunTests::InWhatOrder runOrder() const = 0;
         virtual unsigned int rngSeed() const = 0;
+        virtual bool forceColour() const = 0;
     };
 }