A CI/CD assist device accepts a test template in which some of fields of test content is set to a variable field in which a value is variable. An NOS sets a value compatible with a first environment in the variable field of the test template to generate test data compatible with the first environment. A test device conducts a test on a network service in the first environment by using the test data compatible with the first environment. An NOS sets a value compatible with a second environment in the variable field of the test template to generate test data compatible with the second environment. A test device conducts a test on the network service in the second environment by using the test data compatible with the second environment.