Provider Test Patterns skill

Provider Acceptance Test Patterns

Patterns for writing acceptance tests using terraform-plugin-testing with the Plugin Framework.

Source: HashiCorp Testing Patterns

References (load when needed):

• references/checks.md — statecheck, plancheck, knownvalue types, tfjsonpath, comparers
• references/sweepers.md — sweeper setup, TestMain, dependencies
• references/ephemeral.md — ephemeral resource testing, echoprovider, multi-step patterns

---

Test Lifecycle

The framework runs each TestStep through: plan → apply → refresh → final plan. If the final plan shows a diff, the test fails (unless ExpectNonEmptyPlan is set). After all steps, destroy runs followed by CheckDestroy. This means every test automatically verifies that configurations apply cleanly and produce no drift — no assertions needed for that.

---

Test Function Structure

func TestAccExample_basic(t *testing.T) {
    var widget example.Widget
    rName := acctest.RandStringFromCharSet(10, acctest.CharSetAlphaNum)
    resourceName := "example_widget.test"

    resource.ParallelTest(t, resource.TestCase{
        PreCheck:                 func() { testAccPreCheck(t) },
        ProtoV6ProviderFactories: testAccProtoV6ProviderFactories,
        CheckDestroy:             testAccCheckExampleDestroy,
        Steps: []resource.TestStep{
            {
                Config: testAccExampleConfig_basic(rName),
                ConfigStateChecks: []statecheck.StateCheck{
                    stateCheckExampleExists(resourceName, &widget),
                    statecheck.ExpectKnownValue(resourceName,
                        tfjsonpath.New("name"), knownvalue.StringExact(rName)),
                    statecheck.ExpectKnownValue(resourceName,
                        tfjsonpath.New("id"), knownvalue.NotNull()),
                },
            },
        },
    })
}

Use resource.ParallelTest by default. Use resource.Test only when tests share state or cannot run concurrently.

---

Provider Factory

// provider_test.go — Plugin Framework with Protocol 6 (use Protocol5 variant if needed)
var testAccProtoV6ProviderFactories = map[string]func() (tfprotov6.ProviderServer, error){
    "example": providerserver.NewProtocol6WithError(New("test")()),
}

---

TestCase Fields

Field	Purpose
PreCheck	func() — verify prerequisites (env vars, API access)
ProtoV6ProviderFactories	Plugin Framework provider factories
CheckDestroy	TestCheckFunc — verify resources destroyed after all steps
Steps	[]TestStep — sequential test operations
TerraformVersionChecks	[]tfversion.TerraformVersionCheck — gate by CLI version

---

TestStep Fields

Config Mode

Field	Purpose
Config	Inline HCL string to apply
ConfigStateChecks	[]statecheck.StateCheck — modern assertions (preferred)
ConfigPlanChecks	resource.ConfigPlanChecks{PreApply: []plancheck.PlanCheck{...}}
ExpectError	*regexp.Regexp — expect failure matching pattern
ExpectNonEmptyPlan	bool — expect non-empty plan after apply
PlanOnly	bool — plan without applying
Destroy	bool — run destroy step
PreConfig	func() — setup before step

Import Mode

Field	Purpose
ImportState	true to enable import mode
ImportStateVerify	Verify imported state matches prior state
ImportStateVerifyIgnore	[]string — attributes to skip during verify
ImportStateKind	resource.ImportBlockWithID — import block generation
ResourceName	Resource address to import
ImportStateId	Override the ID used for import

---

Check Functions

Modern: ConfigStateChecks (preferred)

Type-safe with aggregated error reporting. Compose built-in checks with custom statecheck.StateCheck implementations. See references/checks.md for full knownvalue types, tfjsonpath navigation, and comparers.

ConfigStateChecks: []statecheck.StateCheck{
    stateCheckExampleExists(resourceName, &widget),
    statecheck.ExpectKnownValue(resourceName,
        tfjsonpath.New("name"), knownvalue.StringExact("my-widget")),
    statecheck.ExpectKnownValue(resourceName,
        tfjsonpath.New("enabled"), knownvalue.Bool(true)),
    statecheck.ExpectKnownValue(resourceName,
        tfjsonpath.New("id"), knownvalue.NotNull()),
    statecheck.ExpectSensitiveValue(resourceName,
        tfjsonpath.New("api_key")),
},

Do not mix Check (legacy) and ConfigStateChecks in the same step.

Legacy: Check (for CheckDestroy and migration)

CheckDestroy on TestCase requires TestCheckFunc. The Check field on TestStep also accepts TestCheckFunc but prefer ConfigStateChecks for new tests.

Check: resource.ComposeAggregateTestCheckFunc(
    resource.TestCheckResourceAttr(name, "key", "expected"),
    resource.TestCheckResourceAttrSet(name, "id"),
    resource.TestCheckNoResourceAttr(name, "removed"),
    resource.TestMatchResourceAttr(name, "url", regexp.MustCompile(`^https://`)),
    resource.TestCheckResourceAttrPair(res1, "ref_id", res2, "id"),
),

ComposeAggregateTestCheckFunc reports all errors; ComposeTestCheckFunc fails fast on the first.

---

Config Helpers

Use numbered format verbs — %[1]q for quoted strings, %[1]s for raw:

func testAccExampleConfig_basic(rName string) string {
    return fmt.Sprintf(`
resource "example_widget" "test" {
  name = %[1]q
}
`, rName)
}

func testAccExampleConfig_full(rName, description string) string {
    return fmt.Sprintf(`
resource "example_widget" "test" {
  name        = %[1]q
  description = %[2]q
  enabled     = true
}
`, rName, description)
}

---

Scenario Patterns

Basic + Update (combine in one test — updates are supersets of basic)

Steps: []resource.TestStep{
    {
        Config: testAccExampleConfig_basic(rName),
        ConfigStateChecks: []statecheck.StateCheck{
            stateCheckExampleExists(resourceName, &widget),
            statecheck.ExpectKnownValue(resourceName,
                tfjsonpath.New("name"), knownvalue.StringExact(rName)),
        },
    },
    {
        Config: testAccExampleConfig_full(rName, "updated"),
        ConfigStateChecks: []statecheck.StateCheck{
            stateCheckExampleExists(resourceName, &widget),
            statecheck.ExpectKnownValue(resourceName,
                tfjsonpath.New("description"), knownvalue.StringExact("updated")),
        },
    },
},

Import

After a config step, verify import produces identical state. Use ImportStateKind for import block generation:

{
    ResourceName:      resourceName,
    ImportState:       true,
    ImportStateVerify: true,
    ImportStateKind:   resource.ImportBlockWithID,
},

Disappears (resource deleted externally)

{
    Config: testAccExampleConfig_basic(rName),
    ConfigStateChecks: []statecheck.StateCheck{
        stateCheckExampleExists(resourceName, &widget),
        stateCheckExampleDisappears(resourceName),
    },
    ExpectNonEmptyPlan: true,
},

Validation (expect error)

{
    Config:      testAccExampleConfig_invalidName(""),
    ExpectError: regexp.MustCompile(`name must not be empty`),
},

Regression (two-commit workflow)

A proper bug fix uses at least two commits: first commit the regression test (which fails, confirming the bug), then commit the fix (test passes). This lets reviewers independently verify the test reproduces the issue by checking out the first commit, then advancing to the fix.

Name and document regression tests to identify the issue they fix. Include a link to the original bug report when possible.

// TestAccExample_regressionGH1234 verifies fix for https://github.com/org/repo/issues/1234
func TestAccExample_regressionGH1234(t *testing.T) {
    rName := acctest.RandStringFromCharSet(10, acctest.CharSetAlphaNum)
    resourceName := "example_widget.test"

    resource.ParallelTest(t, resource.TestCase{
        PreCheck:                 func() { testAccPreCheck(t) },
        ProtoV6ProviderFactories: testAccProtoV6ProviderFactories,
        CheckDestroy:             testAccCheckExampleDestroy,
        Steps: []resource.TestStep{
            {
                // Reproduce the issue: this config triggered the bug
                Config: testAccExampleConfig_regressionGH1234(rName),
                ConfigStateChecks: []statecheck.StateCheck{
                    stateCheckExampleExists(resourceName, nil),
                    statecheck.ExpectKnownValue(resourceName,
                        tfjsonpath.New("computed_field"), knownvalue.NotNull()),
                },
            },
        },
    })
}

---

Helper Functions

Custom StateCheck: Exists

Implement statecheck.StateCheck for API existence verification. Separate the exists check into its own function for reuse across steps — the source recommends this as a design principle:

type exampleExistsCheck struct {
    resourceAddress string
    widget          *example.Widget
}

func (e exampleExistsCheck) CheckState(ctx context.Context, req statecheck.CheckStateRequest, resp *statecheck.CheckStateResponse) {
    r, err := stateResourceAtAddress(req.State, e.resourceAddress)
    if err != nil {
        resp.Error = err
        return
    }

    id, ok := r.AttributeValues["id"].(string)
    if !ok {
        resp.Error = fmt.Errorf("no id found for %s", e.resourceAddress)
        return
    }

    conn := testAccAPIClient()
    widget, err := conn.GetWidget(id)
    if err != nil {
        resp.Error = fmt.Errorf("%s not found via API: %w", e.resourceAddress, err)
        return
    }

    if e.widget != nil {
        *e.widget = *widget
    }
}

func stateCheckExampleExists(name string, widget *example.Widget) statecheck.StateCheck {
    return exampleExistsCheck{resourceAddress: name, widget: widget}
}

Custom StateCheck: Disappears

Delete a resource via API to simulate external deletion:

type exampleDisappearsCheck struct {
    resourceAddress string
}

func (e exampleDisappearsCheck) CheckState(ctx context.Context, req statecheck.CheckStateRequest, resp *statecheck.CheckStateResponse) {
    r, err := stateResourceAtAddress(req.State, e.resourceAddress)
    if err != nil {
        resp.Error = err
        return
    }

    id := r.AttributeValues["id"].(string)
    conn := testAccAPIClient()
    resp.Error = conn.DeleteWidget(id)
}

func stateCheckExampleDisappears(name string) statecheck.StateCheck {
    return exampleDisappearsCheck{resourceAddress: name}
}

State Resource Lookup (shared utility)

func stateResourceAtAddress(state *tfjson.State, address string) (*tfjson.StateResource, error) {
    if state == nil || state.Values == nil || state.Values.RootModule == nil {
        return nil, fmt.Errorf("no state available")
    }
    for _, r := range state.Values.RootModule.Resources {
        if r.Address == address {
            return r, nil
        }
    }
    return nil, fmt.Errorf("not found in state: %s", address)
}

Destroy Check (TestCheckFunc — required by CheckDestroy)

func testAccCheckExampleDestroy(s *terraform.State) error {
    conn := testAccAPIClient()
    for _, rs := range s.RootModule().Resources {
        if rs.Type != "example_widget" {
            continue
        }
        _, err := conn.GetWidget(rs.Primary.ID)
        if err == nil {
            return fmt.Errorf("widget %s still exists", rs.Primary.ID)
        }
        if !isNotFoundError(err) {
            return err
        }
    }
    return nil
}

PreCheck

func testAccPreCheck(t *testing.T) {
    t.Helper()
    if os.Getenv("EXAMPLE_API_KEY") == "" {
        t.Fatal("EXAMPLE_API_KEY must be set for acceptance tests")
    }
}