provider/aws: Add tests for aws_availability_zones data source

Closing off my other AWS availability zone branch, I'm adding tests for
the existing aws_availability_zones data source.

This closes hashicorp/terraform#4848.

builtin/providers/aws/data_source_availability_zones_test.go

@@ -0,0 +1,80 @@
+package aws
+
+import (
+	"fmt"
+	"reflect"
+	"sort"
+	"strconv"
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/resource"
+	"github.com/hashicorp/terraform/terraform"
+)
+
+func TestAccAWSAvailabilityZones_basic(t *testing.T) {
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccCheckAwsAvailabilityZonesConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsAvailabilityZonesMeta("data.aws_availability_zones.availability_zones"),
+				),
+			},
+		},
+	})
+}
+
+func testAccCheckAwsAvailabilityZonesMeta(n string) resource.TestCheckFunc {
+	return func(s *terraform.State) error {
+		rs, ok := s.RootModule().Resources[n]
+		if !ok {
+			return fmt.Errorf("Can't find AZ resource: %s", n)
+		}
+
+		if rs.Primary.ID == "" {
+			return fmt.Errorf("AZ resource ID not set")
+		}
+
+		actual, err := testAccCheckAwsAvailabilityZonesBuildAvailable(rs.Primary.Attributes)
+		if err != nil {
+			return err
+		}
+
+		expected := actual
+		sort.Strings(expected)
+		if reflect.DeepEqual(expected, actual) != true {
+			return fmt.Errorf("AZs not sorted - expected %v, got %v", expected, actual)
+		}
+		return nil
+	}
+}
+
+func testAccCheckAwsAvailabilityZonesBuildAvailable(attrs map[string]string) ([]string, error) {
+	v, ok := attrs["instance.#"]
+	if !ok {
+		return nil, fmt.Errorf("Available AZ list is missing")
+	}
+	qty, err := strconv.Atoi(v)
+	if err != nil {
+		return nil, err
+	}
+	if qty < 1 {
+		return nil, fmt.Errorf("No AZs found in region, this is probably a bug.")
+	}
+	zones := make([]string, qty)
+	for n := range zones {
+		zone, ok := attrs["instance."+strconv.Itoa(n)]
+		if !ok {
+			return nil, fmt.Errorf("AZ list corrupt, this is definitely a bug")
+		}
+		zones[n] = zone
+	}
+	return zones, nil
+}
+
+const testAccCheckAwsAvailabilityZonesConfig = `
+data "aws_availability_zones" "availability_zones" {
+}
+`