def METHOD_NAME(self, value_type):
    class MockVault:
        def decrypt(self, value, filename=None, obj=None):
            return value
    vault_var = AnsibleVaultEncryptedUnicode(b"vault text")
    vault_var.vault = MockVault()
    actual_value = ensure_type(vault_var, value_type)
    assert actual_value == "vault text"