test: add generator and namespace tests

[SparkYuan]

What type of PR is this?

/kind feature

What this PR does / why we need it:

add generator and namespace tests

[coveralls]

Pull Request Test Coverage Report for Build 5853899783

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.6%) to 71.242%

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Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	74.36%
pkg/engine/operation/parser/spec_parser.go	4	56.1%

Totals
Change from base Build 5821643288:	0.6%
Covered Lines:	5279
Relevant Lines:	7410

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💛 - Coveralls