plancheck: ExpectEmptyPlan Does Not Account for Output Changes

[bflad]

terraform-plugin-testing version

v1.5.1

Relevant provider source code

resource.UnitTest(t, resource.TestCase{
  Steps: []resource.TestStep{
    {
      Config: `output "test" { value = "one" }`,
    },
    {
      Config: `output "test" { value = "two" }`,
      ConfigPlanChecks: resource.ConfigPlanChecks{
        PreApply: []plancheck.PlanCheck{
          plancheck.ExpectEmptyPlan(),
        },
      },
    },
  },
})

Expected Behavior

Given the plan check naming and that in the human-readable plan output that the output change would show, that this assertion would fail the test.

Actual Behavior

Assertion passes and test passes.

Steps to Reproduce

go test

References

• Consider Plan Check for Output Value Changes #221 (fixing the behavior in this report would obviate some need for a separate plan check, although it would still have its own purpose)

[bflad]

Given the similar resource changes only checking of ExpectNonEmptyPlan, I would also presume this applies to that plan check as well in the inverse way.

[bflad]

So this is actually very nuanced. The testing logic currently always calls a refresh command before plan. That refresh will update the output value so the plan views it as a no-op action. The explicit refresh does not need to explicitly be there as it can be done on the plan. Further down the rabbit hole we go!