3fbd6fb6b3 test: Add constructor test (yancy)
Pull request description:
The constructor currently has no test coverage.
ACKs for top commit:
apoelstra:
ACK 3fbd6fb6b3c6dc1f1d5c14b3f3486140a781d0f0; successfully ran local tests
tcharding:
ACK 3fbd6fb6b3
Tree-SHA512: 9819bd058b84a7b633279d12da48c9af7af765fd8dca5d297787872badc431769c026e57b03bf6d907c89a7b7a5c116cda1be98cb6261dd2a6c331276e627cc3