Issue #19: Refactor test cases

config/ci_test.yaml.example

package.json

src/adapter/postgres.spec.ts

src/core/engine.spec.ts

test/postgres/fixture.ts

test/postgres/fixtures/view0.json

test/postgres/fixtures/view1.json

test/postgres/fixtures/view2.json

test/postgres/fixtures/view3.json

test/postgres/fixtures/view4.json

test/postgres/fixtures/view5.json

test/postgres/fixtures/view6.json

test/postgres/fixtures/view7.json

test/postgres/fixtures/view8.json

test/postgres/fixtures/view9.json

test/scenario.ts