feat: Better tests poc (#2917)

I was thinking for some time and finally had a moment to put all this in
writing. This is a PoC of more readable and reusable assertions
(resource and snowflake object ones) and better config builders for
acceptance tests. Check the details in the README.

docs/resources/table_constraint.md

@@ -148,6 +148,5 @@ Required:
 Import is supported using the following syntax:
 
 ```shell
-# format is constraint name ❄ constraint type ❄ database name | schema name | table name
 terraform import snowflake_table_constraint.example 'myconstraintfk❄️FOREIGN KEY❄️databaseName|schemaName|tableName'
 ```

pkg/acceptance/bettertestspoc/assert/commons.go

@@ -0,0 +1,103 @@
+package assert
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
+)
+
+// TestCheckFuncProvider is an interface with just one method providing resource.TestCheckFunc.
+// It allows using it as input the "Check:" in resource.TestStep.
+// It should be used with AssertThat.
+type TestCheckFuncProvider interface {
+	ToTerraformTestCheckFunc(t *testing.T) resource.TestCheckFunc
+}
+
+// AssertThat should be used for "Check:" input in resource.TestStep instead of e.g. resource.ComposeTestCheckFunc.
+// It allows performing all the checks implementing the TestCheckFuncProvider interface.
+func AssertThat(t *testing.T, fs ...TestCheckFuncProvider) resource.TestCheckFunc {
+	t.Helper()
+	return func(s *terraform.State) error {
+		var result []error
+
+		for i, f := range fs {
+			if err := f.ToTerraformTestCheckFunc(t)(s); err != nil {
+				result = append(result, fmt.Errorf("check %d/%d error:\n%w", i+1, len(fs), err))
+			}
+		}
+
+		return errors.Join(result...)
+	}
+}
+
+var _ TestCheckFuncProvider = (*testCheckFuncWrapper)(nil)
+
+type testCheckFuncWrapper struct {
+	f resource.TestCheckFunc
+}
+
+func (w *testCheckFuncWrapper) ToTerraformTestCheckFunc(_ *testing.T) resource.TestCheckFunc {
+	return w.f
+}
+
+// Check allows using the basic terraform checks while using AssertThat.
+// To use, just simply wrap the check in Check.
+func Check(f resource.TestCheckFunc) TestCheckFuncProvider {
+	return &testCheckFuncWrapper{f}
+}
+
+// ImportStateCheckFuncProvider is an interface with just one method providing resource.ImportStateCheckFunc.
+// It allows using it as input the "ImportStateCheck:" in resource.TestStep for import tests.
+// It should be used with AssertThatImport.
+type ImportStateCheckFuncProvider interface {
+	ToTerraformImportStateCheckFunc(t *testing.T) resource.ImportStateCheckFunc
+}
+
+// AssertThatImport should be used for "ImportStateCheck:" input in resource.TestStep instead of e.g. importchecks.ComposeImportStateCheck.
+// It allows performing all the checks implementing the ImportStateCheckFuncProvider interface.
+func AssertThatImport(t *testing.T, fs ...ImportStateCheckFuncProvider) resource.ImportStateCheckFunc {
+	t.Helper()
+	return func(s []*terraform.InstanceState) error {
+		var result []error
+
+		for i, f := range fs {
+			if err := f.ToTerraformImportStateCheckFunc(t)(s); err != nil {
+				result = append(result, fmt.Errorf("check %d/%d error:\n%w", i+1, len(fs), err))
+			}
+		}
+
+		return errors.Join(result...)
+	}
+}
+
+var _ ImportStateCheckFuncProvider = (*importStateCheckFuncWrapper)(nil)
+
+type importStateCheckFuncWrapper struct {
+	f resource.ImportStateCheckFunc
+}
+
+func (w *importStateCheckFuncWrapper) ToTerraformImportStateCheckFunc(_ *testing.T) resource.ImportStateCheckFunc {
+	return w.f
+}
+
+// CheckImport allows using the basic terraform import checks while using AssertThatImport.
+// To use, just simply wrap the check in CheckImport.
+func CheckImport(f resource.ImportStateCheckFunc) ImportStateCheckFuncProvider {
+	return &importStateCheckFuncWrapper{f}
+}
+
+// InPlaceAssertionVerifier is an interface providing a method allowing verifying all the prepared assertions in place.
+// It does not return function like TestCheckFuncProvider or ImportStateCheckFuncProvider; it runs all the assertions in place instead.
+type InPlaceAssertionVerifier interface {
+	VerifyAll(t *testing.T)
+}
+
+// AssertThatObject should be used in the SDK tests for created object validation.
+// It verifies all the prepared assertions in place.
+func AssertThatObject(t *testing.T, objectAssert InPlaceAssertionVerifier) {
+	t.Helper()
+	objectAssert.VerifyAll(t)
+}

pkg/acceptance/bettertestspoc/assert/resource_assertions.go

@@ -0,0 +1,133 @@
+package assert
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/Snowflake-Labs/terraform-provider-snowflake/pkg/acceptance/importchecks"
+	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
+)
+
+var (
+	_ TestCheckFuncProvider        = (*ResourceAssert)(nil)
+	_ ImportStateCheckFuncProvider = (*ResourceAssert)(nil)
+)
+
+// ResourceAssert is an embeddable struct that should be used to construct new resource assertions (for resource, show output, parameters, etc.).
+// It implements both TestCheckFuncProvider and ImportStateCheckFuncProvider which makes it easy to create new resource assertions.
+type ResourceAssert struct {
+	name       string
+	id         string
+	prefix     string
+	assertions []resourceAssertion
+}
+
+// NewResourceAssert creates a ResourceAssert where the resource name should be used as a key for assertions.
+func NewResourceAssert(name string, prefix string) *ResourceAssert {
+	return &ResourceAssert{
+		name:       name,
+		prefix:     prefix,
+		assertions: make([]resourceAssertion, 0),
+	}
+}
+
+// NewImportedResourceAssert creates a ResourceAssert where the resource id should be used as a key for assertions.
+func NewImportedResourceAssert(id string, prefix string) *ResourceAssert {
+	return &ResourceAssert{
+		id:         id,
+		prefix:     prefix,
+		assertions: make([]resourceAssertion, 0),
+	}
+}
+
+type resourceAssertionType string
+
+const (
+	resourceAssertionTypeValueSet    = "VALUE_SET"
+	resourceAssertionTypeValueNotSet = "VALUE_NOT_SET"
+)
+
+type resourceAssertion struct {
+	fieldName             string
+	expectedValue         string
+	resourceAssertionType resourceAssertionType
+}
+
+func valueSet(fieldName string, expected string) resourceAssertion {
+	return resourceAssertion{fieldName: fieldName, expectedValue: expected, resourceAssertionType: resourceAssertionTypeValueSet}
+}
+
+func valueNotSet(fieldName string) resourceAssertion {
+	return resourceAssertion{fieldName: fieldName, resourceAssertionType: resourceAssertionTypeValueNotSet}
+}
+
+const showOutputPrefix = "show_output.0."
+
+func showOutputValueSet(fieldName string, expected string) resourceAssertion {
+	return resourceAssertion{fieldName: showOutputPrefix + fieldName, expectedValue: expected, resourceAssertionType: resourceAssertionTypeValueSet}
+}
+
+const (
+	parametersPrefix      = "parameters.0."
+	parametersValueSuffix = ".0.value"
+	parametersLevelSuffix = ".0.level"
+)
+
+func parameterValueSet(fieldName string, expected string) resourceAssertion {
+	return resourceAssertion{fieldName: parametersPrefix + fieldName + parametersValueSuffix, expectedValue: expected, resourceAssertionType: resourceAssertionTypeValueSet}
+}
+
+func parameterLevelSet(fieldName string, expected string) resourceAssertion {
+	return resourceAssertion{fieldName: parametersPrefix + fieldName + parametersLevelSuffix, expectedValue: expected, resourceAssertionType: resourceAssertionTypeValueSet}
+}
+
+// ToTerraformTestCheckFunc implements TestCheckFuncProvider to allow easier creation of new resource assertions.
+// It goes through all the assertion accumulated earlier and gathers the results of the checks.
+func (r *ResourceAssert) ToTerraformTestCheckFunc(t *testing.T) resource.TestCheckFunc {
+	t.Helper()
+	return func(s *terraform.State) error {
+		var result []error
+
+		for i, a := range r.assertions {
+			switch a.resourceAssertionType {
+			case resourceAssertionTypeValueSet:
+				if err := resource.TestCheckResourceAttr(r.name, a.fieldName, a.expectedValue)(s); err != nil {
+					errCut, _ := strings.CutPrefix(err.Error(), fmt.Sprintf("%s: ", r.name))
+					result = append(result, fmt.Errorf("%s %s assertion [%d/%d]: failed with error: %s", r.name, r.prefix, i+1, len(r.assertions), errCut))
+				}
+			case resourceAssertionTypeValueNotSet:
+				if err := resource.TestCheckNoResourceAttr(r.name, a.fieldName)(s); err != nil {
+					errCut, _ := strings.CutPrefix(err.Error(), fmt.Sprintf("%s: ", r.name))
+					result = append(result, fmt.Errorf("%s %s assertion [%d/%d]: failed with error: %s", r.name, r.prefix, i+1, len(r.assertions), errCut))
+				}
+			}
+		}
+
+		return errors.Join(result...)
+	}
+}
+
+// ToTerraformImportStateCheckFunc implements ImportStateCheckFuncProvider to allow easier creation of new resource assertions.
+// It goes through all the assertion accumulated earlier and gathers the results of the checks.
+func (r *ResourceAssert) ToTerraformImportStateCheckFunc(t *testing.T) resource.ImportStateCheckFunc {
+	t.Helper()
+	return func(s []*terraform.InstanceState) error {
+		var result []error
+
+		for i, a := range r.assertions {
+			switch a.resourceAssertionType {
+			case resourceAssertionTypeValueSet:
+				if err := importchecks.TestCheckResourceAttrInstanceState(r.id, a.fieldName, a.expectedValue)(s); err != nil {
+					result = append(result, fmt.Errorf("%s %s assertion [%d/%d]: failed with error: %w", r.id, r.prefix, i+1, len(r.assertions), err))
+				}
+			case resourceAssertionTypeValueNotSet:
+				panic("implement")
+			}
+		}
+
+		return errors.Join(result...)
+	}
+}

pkg/acceptance/bettertestspoc/assert/snowflake_assertions.go

@@ -0,0 +1,103 @@
+package assert
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/Snowflake-Labs/terraform-provider-snowflake/pkg/sdk"
+	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
+	"github.com/stretchr/testify/require"
+)
+
+type (
+	assertSdk[T any]                              func(*testing.T, T) error
+	objectProvider[T any, I sdk.ObjectIdentifier] func(*testing.T, I) (*T, error)
+)
+
+// SnowflakeObjectAssert is an embeddable struct that should be used to construct new Snowflake object assertions.
+// It implements both TestCheckFuncProvider and ImportStateCheckFuncProvider which makes it easy to create new resource assertions.
+type SnowflakeObjectAssert[T any, I sdk.ObjectIdentifier] struct {
+	assertions []assertSdk[*T]
+	id         I
+	objectType sdk.ObjectType
+	object     *T
+	provider   objectProvider[T, I]
+}
+
+// NewSnowflakeObjectAssertWithProvider creates a SnowflakeObjectAssert with id and the provider.
+// Object to check is lazily fetched from Snowflake when the checks are being run.
+func NewSnowflakeObjectAssertWithProvider[T any, I sdk.ObjectIdentifier](objectType sdk.ObjectType, id I, provider objectProvider[T, I]) *SnowflakeObjectAssert[T, I] {
+	return &SnowflakeObjectAssert[T, I]{
+		assertions: make([]assertSdk[*T], 0),
+		id:         id,
+		objectType: objectType,
+		provider:   provider,
+	}
+}
+
+// NewSnowflakeObjectAssertWithObject creates a SnowflakeObjectAssert with object that was already fetched from Snowflake.
+// All the checks are run against the given object.
+func NewSnowflakeObjectAssertWithObject[T any, I sdk.ObjectIdentifier](objectType sdk.ObjectType, id I, object *T) *SnowflakeObjectAssert[T, I] {
+	return &SnowflakeObjectAssert[T, I]{
+		assertions: make([]assertSdk[*T], 0),
+		id:         id,
+		objectType: objectType,
+		object:     object,
+	}
+}
+
+// ToTerraformTestCheckFunc implements TestCheckFuncProvider to allow easier creation of new Snowflake object assertions.
+// It goes through all the assertion accumulated earlier and gathers the results of the checks.
+func (s *SnowflakeObjectAssert[_, _]) ToTerraformTestCheckFunc(t *testing.T) resource.TestCheckFunc {
+	t.Helper()
+	return func(_ *terraform.State) error {
+		return s.runSnowflakeObjectsAssertions(t)
+	}
+}
+
+// ToTerraformImportStateCheckFunc implements ImportStateCheckFuncProvider to allow easier creation of new Snowflake object assertions.
+// It goes through all the assertion accumulated earlier and gathers the results of the checks.
+func (s *SnowflakeObjectAssert[_, _]) ToTerraformImportStateCheckFunc(t *testing.T) resource.ImportStateCheckFunc {
+	t.Helper()
+	return func(_ []*terraform.InstanceState) error {
+		return s.runSnowflakeObjectsAssertions(t)
+	}
+}
+
+// VerifyAll implements InPlaceAssertionVerifier to allow easier creation of new Snowflake object assertions.
+// It verifies all the assertions accumulated earlier and gathers the results of the checks.
+func (s *SnowflakeObjectAssert[_, _]) VerifyAll(t *testing.T) {
+	t.Helper()
+	err := s.runSnowflakeObjectsAssertions(t)
+	require.NoError(t, err)
+}
+
+func (s *SnowflakeObjectAssert[T, _]) runSnowflakeObjectsAssertions(t *testing.T) error {
+	t.Helper()
+
+	var sdkObject *T
+	var err error
+	switch {
+	case s.object != nil:
+		sdkObject = s.object
+	case s.provider != nil:
+		sdkObject, err = s.provider(t, s.id)
+		if err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("cannot proceed with object %s[%s] assertion: object or provider must be specified", s.objectType, s.id.FullyQualifiedName())
+	}
+
+	var result []error
+
+	for i, assertion := range s.assertions {
+		if err = assertion(t, sdkObject); err != nil {
+			result = append(result, fmt.Errorf("object %s[%s] assertion [%d/%d]: failed with error: %w", s.objectType, s.id.FullyQualifiedName(), i+1, len(s.assertions), err))
+		}
+	}
+
+	return errors.Join(result...)
+}