err = erasure.DecodeDataAndParityBlocks(context.Background(), encoded)
		} else {
			err = erasure.DecodeDataBlocks(encoded)
		}

		if err == nil && test.shouldFail {
			t.Errorf("Test %d: test should fail but it passed", i)
		}
		if err != nil && !test.shouldFail {
			t.Errorf("Test %d: test should pass but it failed: %v", i, err)
		}

		decoded := encoded
		if !test.shouldFail {
			if test.reconstructParity {