After applying this test step and performing a `terraform refresh`, the plan was not empty

Can anyone give me a better idea as to what causes this error to occur when testing a provider?

resource_project_merge_strategies_test.go:52: Step 1/2 error: After applying this test step and performing a `terraform refresh`, the plan was not empty.
        stdout


        Terraform used the selected providers to generate the following execution
        plan. Resource actions are indicated with the following symbols:
          ~ update in-place

        Terraform will perform the following actions:

          # bitbucketserver_project_merge_strategies.test will be updated in-place
          ~ resource "bitbucketserver_project_merge_strategies" "test" {
              + defaultstrategy = (known after apply)
                id              = "TEST7650513280575298973"
                # (2 unchanged attributes hidden)

              - strategy {
                  - default = false -> null
                  - id      = "no-ff" -> null
                }
              + strategy {
                  + default = true
                  + id      = "no-ff"
                }
            }

        Plan: 0 to add, 1 to change, 0 to destroy.
--- FAIL: TestAccBitbucketResourceProjectMergeStrategies (4.38s)

Terraform SDK version is v2.20.0.

Nevermind. I forgot I had a d.Set("strategy") somewhere and that isn’t a computed value.