t.Fatalf("test %d, Write() = (%d, %v), want (%d, %v)", i, got, err, tf.wantCnt, tf.wantErr)
					}
				case testReadFrom:
					f := &testFile{ops: tf.ops}
					got, err := tw.readFrom(f)
					if _, ok := err.(testError); ok {
						t.Errorf("test %d, ReadFrom(): %v", i, err)
					} else if got != tf.wantCnt || !equalError(err, tf.wantErr) {
						t.Errorf("test %d, ReadFrom() = (%d, %v), want (%d, %v)", i, got, err, tf.wantCnt, tf.wantErr)