Adding ExpectKnownValue state check (#266)

statecheck/expect_known_value.go

@@ -0,0 +1,94 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package statecheck
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+
+	tfjson "github.com/hashicorp/terraform-json"
+
+	"github.com/hashicorp/terraform-plugin-testing/knownvalue"
+	"github.com/hashicorp/terraform-plugin-testing/tfjsonpath"
+)
+
+// Resource State Check
+var _ StateCheck = expectKnownValue{}
+
+type expectKnownValue struct {
+	resourceAddress string
+	attributePath   tfjsonpath.Path
+	knownValue      knownvalue.Check
+}
+
+// CheckState implements the state check logic.
+func (e expectKnownValue) CheckState(ctx context.Context, req CheckStateRequest, resp *CheckStateResponse) {
+	var rc *tfjson.StateResource
+
+	if req.State.Values == nil {
+		resp.Error = fmt.Errorf("state does not contain any state values")
+	}
+
+	if req.State.Values.RootModule == nil {
+		resp.Error = fmt.Errorf("state does not contain a root module")
+	}
+
+	for _, resourceChange := range req.State.Values.RootModule.Resources {
+		if e.resourceAddress == resourceChange.Address {
+			rc = resourceChange
+
+			break
+		}
+	}
+
+	if rc == nil {
+		resp.Error = fmt.Errorf("%s - Resource not found in state", e.resourceAddress)
+
+		return
+	}
+
+	result, err := tfjsonpath.Traverse(rc.AttributeValues, e.attributePath)
+
+	if err != nil {
+		resp.Error = err
+
+		return
+	}
+
+	if result == nil {
+		resp.Error = fmt.Errorf("value is null")
+
+		return
+	}
+
+	switch reflect.TypeOf(result).Kind() {
+	case reflect.Bool,
+		reflect.Map,
+		reflect.Slice,
+		reflect.String:
+		if err := e.knownValue.CheckValue(result); err != nil {
+			resp.Error = err
+
+			return
+		}
+	default:
+		errorStr := fmt.Sprintf("unrecognised attribute type: %T, known value type is %T", result, e.knownValue)
+		errorStr += "\n\nThis is an error in statecheck.ExpectKnownValue.\nPlease report this to the maintainers."
+
+		resp.Error = fmt.Errorf(errorStr)
+
+		return
+	}
+}
+
+// ExpectKnownValue returns a state check that asserts that the specified attribute at the given resource
+// has a known type and value.
+func ExpectKnownValue(resourceAddress string, attributePath tfjsonpath.Path, knownValue knownvalue.Check) StateCheck {
+	return expectKnownValue{
+		resourceAddress: resourceAddress,
+		attributePath:   attributePath,
+		knownValue:      knownValue,
+	}
+}