add getColourSupport()

src/UnixTerminal.php

@@ -34,6 +34,11 @@ class UnixTerminal implements Terminal
      * @var int
      */
     private $height;
+
+    /**
+     * @var int;
+     */
+    private $colourSupport;
 
     /**
      * @var string
@@ -74,6 +79,11 @@ public function getHeight() : int
         return $this->height ?: $this->height = (int) exec('tput lines');
     }
 
+    public function getColourSupport() : int
+    {
+        return $this->colourSupport ?: $this->colourSupport = (int) exec('tput colors');
+    }
+
     private function getOriginalConfiguration() : string
     {
         return $this->originalConfiguration ?: $this->originalConfiguration = exec('stty -g');

test/UnixTerminalTest.php

@@ -284,4 +284,16 @@ public function testWriteForwardsToOutput() : void
 
         self::assertEquals('My awesome string', $output->fetch());
     }
+
+    public function testGetColourSupport() : void
+    {
+        $input  = $this->createMock(InputStream::class);
+        $output = new BufferedOutput;
+
+        $terminal = new UnixTerminal($input, $output);
+
+        // Travis terminal supports 8 colours, but just in case
+        // in ever changes I'll add the 256 colors possibility too
+        self::assertTrue($terminal->getColourSupport() === 8 || $terminal->getColourSupport() === 256);
+    }
 }