provider/test: Add test of data source count.index

This adds a unit test to the test provider that verifies count.index
behaves correctly. Although not ideal this is hard to implement as a
context test without changing around the (non helper/schema)
implementation of the x_data_source.

builtin/providers/test/data_source.go

@@ -11,11 +11,21 @@ func testDataSource() *schema.Resource {
 		Read: testDataSourceRead,
 
 		Schema: map[string]*schema.Schema{
-			"list": &schema.Schema{
+			"list": {
 				Type:     schema.TypeList,
 				Computed: true,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 			},
+
+			"input": {
+				Type:     schema.TypeString,
+				Optional: true,
+			},
+
+			"output": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
 		},
 	}
 }
@@ -24,5 +34,11 @@ func testDataSourceRead(d *schema.ResourceData, meta interface{}) error {
 	d.SetId(time.Now().UTC().String())
 	d.Set("list", []interface{}{"one", "two", "three"})
 
+	if input, hasInput := d.GetOk("input"); hasInput {
+		d.Set("output", input)
+	} else {
+		d.Set("output", "some output")
+	}
+
 	return nil
 }

builtin/providers/test/data_source_test.go

@@ -0,0 +1,57 @@
+package test
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/resource"
+	"github.com/hashicorp/terraform/terraform"
+)
+
+func TestDataSource_dataSourceCount(t *testing.T) {
+	resource.UnitTest(t, resource.TestCase{
+		Providers: testAccProviders,
+		CheckDestroy: func(s *terraform.State) error {
+			return nil
+		},
+		Steps: []resource.TestStep{
+			{
+				Config: strings.TrimSpace(`
+data "test_data_source" "test" {
+  count = 3
+  input = "count-${count.index}"
+}
+
+resource "test_resource" "foo" {
+  required     = "yep"
+  required_map = {
+    key = "value"
+  }
+
+  list = ["${data.test_data_source.test.*.output}"]
+}
+				`),
+				Check: func(s *terraform.State) error {
+					res, hasRes := s.RootModule().Resources["test_resource.foo"]
+					if !hasRes {
+						return errors.New("No test_resource.foo in state")
+					}
+					if res.Primary.Attributes["list.#"] != "3" {
+						return errors.New("Wrong list.#, expected 3")
+					}
+					if res.Primary.Attributes["list.0"] != "count-0" {
+						return errors.New("Wrong list.0, expected count-0")
+					}
+					if res.Primary.Attributes["list.1"] != "count-1" {
+						return errors.New("Wrong list.0, expected count-1")
+					}
+					if res.Primary.Attributes["list.2"] != "count-2" {
+						return errors.New("Wrong list.0, expected count-2")
+					}
+					return nil
+				},
+			},
+		},
+	})
+}

builtin/providers/test/resource.go

@@ -97,6 +97,13 @@ func testResource() *schema.Resource {
 				Type:     schema.TypeMap,
 				Computed: true,
 			},
+			"list": {
+				Type:     schema.TypeList,
+				Optional: true,
+				Elem: &schema.Schema{
+					Type: schema.TypeString,
+				},
+			},
 			"list_of_map": {
 				Type:     schema.TypeList,
 				Optional: true,