Add syscall mock

sysfs/i2c_device.go

@@ -18,21 +18,16 @@ func NewI2cDevice(location string, address byte) (io.ReadWriteCloser, error) {
 		return nil, err
 	}
 
-	errno := ioctrl(file, address)
+	_, _, errno := Syscall(
+		syscall.SYS_IOCTL,
+		file.Fd(),
+		I2CSlave,
+		uintptr(address),
+	)
 
 	if errno != 0 {
 		return nil, errors.New(fmt.Sprintf("Failed with syscall.Errno %v", errno))
 	}
 
 	return file, nil
 }
-
-var ioctrl = func(file File, address byte) syscall.Errno {
-	_, _, errno := syscall.Syscall(
-		syscall.SYS_IOCTL,
-		file.Fd(),
-		I2CSlave, uintptr(address),
-	)
-
-	return errno
-}

sysfs/i2c_device_test.go

@@ -4,7 +4,6 @@ import (
 	"github.com/hybridgroup/gobot"
 	"io"
 	"os"
-	"syscall"
 	"testing"
 )
 
@@ -24,9 +23,7 @@ func TestNewI2cDevice(t *testing.T) {
 	i, err = NewI2cDevice("/dev/i2c-1", 0xff)
 	gobot.Refute(t, err, nil)
 
-	ioctrl = func(file File, address byte) syscall.Errno {
-		return 0
-	}
+	SetSyscall(&MockSyscall{})
 
 	i, err = NewI2cDevice("/dev/i2c-1", 0xff)
 	gobot.Assert(t, err, nil)

sysfs/syscall.go

@@ -0,0 +1,30 @@
+package sysfs
+
+import (
+	"syscall"
+)
+
+type SystemCaller interface {
+	Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
+}
+
+type NativeSyscall struct{}
+type MockSyscall struct{}
+
+var sys SystemCaller = &NativeSyscall{}
+
+func SetSyscall(s SystemCaller) {
+	sys = s
+}
+
+func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+	return sys.Syscall(trap, a1, a2, a3)
+}
+
+func (sys *NativeSyscall) Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+	return syscall.Syscall(trap, a1, a2, a3)
+}
+
+func (sys *MockSyscall) Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
+	return 0, 0, 0
+}