helper/config: Validator

/cc @pearkes - Here is the beginning of that helper. It can't really validate
deeper keys (i.e. listeners in ELB), but my goal is for it to support that
soon. Working on it.

helper/config/validator.go

@@ -0,0 +1,48 @@
+package config
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/terraform/terraform"
+)
+
+// Validator is a helper that helps you validate the configuration
+// of your resource, resource provider, etc.
+type Validator struct {
+	Required []string
+	Optional []string
+}
+
+func (v *Validator) Validate(
+	c *terraform.ResourceConfig) (ws []string, es []error) {
+	keySet := make(map[string]bool)
+	reqSet := make(map[string]struct{})
+	for _, k := range v.Required {
+		keySet[k] = true
+		reqSet[k] = struct{}{}
+	}
+	for _, k := range v.Optional {
+		keySet[k] = false
+	}
+
+	// Find any unknown keys used and mark off required keys that
+	// we have set.
+	for k, _ := range c.Raw {
+		_, ok := keySet[k]
+		if !ok {
+			es = append(es, fmt.Errorf(
+				"Unknown configuration key: %s", k))
+			continue
+		}
+
+		delete(reqSet, k)
+	}
+
+	// Check what keys are required that we didn't set
+	for k, _ := range reqSet {
+		es = append(es, fmt.Errorf(
+			"Required key is not set: %s", k))
+	}
+
+	return
+}

helper/config/validator_test.go

@@ -0,0 +1,67 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform/config"
+	"github.com/hashicorp/terraform/terraform"
+)
+
+func TestValidator(t *testing.T) {
+	v := &Validator{
+		Required: []string{"foo"},
+		Optional: []string{"bar"},
+	}
+
+	var c *terraform.ResourceConfig
+
+	// Valid
+	c = testConfig(t, map[string]interface{}{
+		"foo": "bar",
+	})
+	testValid(t, v, c)
+
+	// Missing required
+	c = testConfig(t, map[string]interface{}{
+		"bar": "baz",
+	})
+	testInvalid(t, v, c)
+
+	// Unknown key
+	c = testConfig(t, map[string]interface{}{
+		"foo":  "bar",
+		"what": "what",
+	})
+	testInvalid(t, v, c)
+}
+
+func testConfig(
+	t *testing.T,
+	c map[string]interface{}) *terraform.ResourceConfig {
+	r, err := config.NewRawConfig(c)
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+
+	return terraform.NewResourceConfig(r)
+}
+
+func testInvalid(t *testing.T, v *Validator, c *terraform.ResourceConfig) {
+	ws, es := v.Validate(c)
+	if len(ws) > 0 {
+		t.Fatalf("bad: %#v", ws)
+	}
+	if len(es) == 0 {
+		t.Fatalf("bad: %#v", es)
+	}
+}
+
+func testValid(t *testing.T, v *Validator, c *terraform.ResourceConfig) {
+	ws, es := v.Validate(c)
+	if len(ws) > 0 {
+		t.Fatalf("bad: %#v", ws)
+	}
+	if len(es) > 0 {
+		t.Fatalf("bad: %#v", es)
+	}
+}