Enhance Sonyflake error handling by adding tests for invalid machine IDs, including cases for too large and negative values. (#73)

v2/sonyflake.go

@@ -157,6 +157,10 @@ func New(st Settings) (*Sonyflake, error) {
 		return nil, err
 	}
 
+	if sf.machine < 0 || sf.machine >= 1<<sf.bitsMachine {
+		return nil, ErrInvalidMachineID
+	}
+
 	if st.CheckMachineID != nil && !st.CheckMachineID(sf.machine) {
 		return nil, ErrInvalidMachineID
 	}

v2/sonyflake_test.go

@@ -65,6 +65,24 @@ func TestNew(t *testing.T) {
 			},
 			err: errGetMachineID,
 		},
+		{
+			name: "too large machine id",
+			settings: Settings{
+				MachineID: func() (int, error) {
+					return 1 << defaultBitsMachine, nil
+				},
+			},
+			err: ErrInvalidMachineID,
+		},
+		{
+			name: "negative machine id",
+			settings: Settings{
+				MachineID: func() (int, error) {
+					return -1, nil
+				},
+			},
+			err: ErrInvalidMachineID,
+		},
 		{
 			name: "invalid machine id",
 			settings: Settings{