tester: improve API surface and implement one more test function in lis2mdl driver

Signed-off-by: deadprogram <ron@hybridgroup.com>

tester/device.go

@@ -1,38 +1,63 @@
 package tester
 
-import (
-	qt "github.com/frankban/quicktest"
-)
-
-const maxRegisters = 200
+// MaxRegisters is the maximum number of registers supported for a Device.
+const MaxRegisters = 200
 
 // I2CDevice represents a mock I2C device on a mock I2C bus.
 type I2CDevice struct {
-	C    *qt.C
-	Addr uint8
+	c Failer
+	// addr is the i2c device address.
+	addr uint8
 	// Registers holds the device registers. It can be inspected
 	// or changed as desired for testing.
-	Registers [maxRegisters]uint8
+	registers [MaxRegisters]uint8
 	// If Err is non-nil, it will be returned as the error from the
 	// I2C methods.
 	Err error
 }
 
 // NewI2CDevice returns a new mock I2C device.
-func NewI2CDevice(c *qt.C, addr uint8) *I2CDevice {
+func NewI2CDevice(c Failer, addr uint8) *I2CDevice {
 	return &I2CDevice{
-		C:    c,
-		Addr: addr,
+		c:    c,
+		addr: addr,
 	}
 }
 
+// Addr returns the Device address.
+func (d *I2CDevice) Addr() uint8 {
+	return d.addr
+}
+
+// SetupRegisters sets all of the Device registers.
+// It is intended to be used when setting up a fake device
+// for testing expected vs. actual values.
+func (d *I2CDevice) SetupRegisters(regs []uint8) {
+	if len(regs) > MaxRegisters {
+		panic("exceeded maximum number of registers for fake device")
+	}
+	for k, v := range regs {
+		d.registers[k] = v
+	}
+}
+
+// SetupRegister sets one of the Device registers.
+// It is intended to be used when setting up a fake device
+// for testing expected vs. actual values.
+func (d *I2CDevice) SetupRegister(r, v uint8) {
+	if r > MaxRegisters {
+		panic("exceeded maximum number of registers for fake device")
+	}
+	d.registers[r] = v
+}
+
 // ReadRegister implements I2C.ReadRegister.
 func (d *I2CDevice) ReadRegister(r uint8, buf []byte) error {
 	if d.Err != nil {
 		return d.Err
 	}
 	d.AssertRegisterRange(r, buf)
-	copy(buf, d.Registers[r:])
+	copy(buf, d.registers[r:])
 	return nil
 }
 
@@ -42,17 +67,17 @@ func (d *I2CDevice) WriteRegister(r uint8, buf []byte) error {
 		return d.Err
 	}
 	d.AssertRegisterRange(r, buf)
-	copy(d.Registers[r:], buf)
+	copy(d.registers[r:], buf)
 	return nil
 }
 
 // AssertRegisterRange asserts that reading or writing the given
 // register and subsequent registers is in range of the available registers.
 func (d *I2CDevice) AssertRegisterRange(r uint8, buf []byte) {
-	if int(r) >= len(d.Registers) {
-		d.C.Fatalf("register read/write [%#x, %#x] start out of range", r, int(r)+len(buf))
+	if int(r) >= len(d.registers) {
+		d.c.Fatalf("register read/write [%#x, %#x] start out of range", r, int(r)+len(buf))
 	}
-	if int(r)+len(buf) > len(d.Registers) {
-		d.C.Fatalf("register read/write [%#x, %#x] end out of range", r, int(r)+len(buf))
+	if int(r)+len(buf) > len(d.registers) {
+		d.c.Fatalf("register read/write [%#x, %#x] end out of range", r, int(r)+len(buf))
 	}
 }