test: fix Fake classes and test code to pass

Author: kenjis

tests/Fake/CI_Email.php

@@ -6,4 +6,8 @@
 
 class CI_Email
 {
+    public function to(string $to): CI_Email
+    {
+        return $this;
+    }
 }

tests/Fake/CI_Input.php

@@ -6,8 +6,18 @@
 
 class CI_Input
 {
-    public function method(): string
+    public function method(bool $upper = false): string
     {
         return 'GET';
     }
+
+    /**
+     * @param mixed $index
+     *
+     * @return mixed
+     */
+    public function get($index = null, bool $xss_clean = false)
+    {
+        return 'GET value';
+    }
 }

tests/TestDoubleTest.php

@@ -78,7 +78,7 @@ public function test_getDouble_method_returns_execption(): void
         };
         $mock = $this->getDouble(CI_Input::class, ['method' => $ret]);
 
-        $mock->method('abc', 'def');
+        $mock->method();
     }
 
     public function test_getDouble_constructor_param(): void