COMPMID-765: Fixed output accessor in LeNet example, and disabled colors when not running in a terminal

Change-Id: I4ec90803c5dc41b0cee05c36113ae3f189564d58
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/117831
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/tests/framework/command_line/CommonOptions.cpp b/tests/framework/command_line/CommonOptions.cpp
index 631981b..e0b93f6 100644
--- a/tests/framework/command_line/CommonOptions.cpp
+++ b/tests/framework/command_line/CommonOptions.cpp
@@ -26,6 +26,7 @@
 #include "../Framework.h"
 #include "../printers/Printers.h"
 #include "CommandLineParser.h"
+#include <unistd.h>
 
 namespace arm_compute
 {
@@ -42,7 +43,7 @@
       log_file(parser.add_option<SimpleOption<std::string>>("log-file")),
       log_level(),
       throw_errors(parser.add_option<ToggleOption>("throw-errors")),
-      color_output(parser.add_option<ToggleOption>("color-output", true)),
+      color_output(parser.add_option<ToggleOption>("color-output", isatty(STDOUT_FILENO))), // Only enable colors by default if we're running in a terminal
       pretty_console(parser.add_option<ToggleOption>("pretty-console", false)),
       json_file(parser.add_option<SimpleOption<std::string>>("json-file")),
       pretty_file(parser.add_option<SimpleOption<std::string>>("pretty-file")),