Merge pull request #532 from gruntwork-io/yori-test-nil-conversion

Handle nil in input vars

modules/terraform/format.go

@@ -182,6 +182,10 @@ func mapToHclString(m map[string]interface{}) string {
 // Convert a primitive, such as a bool, int, or string, to an HCL string. If this isn't a primitive, force its value
 // using Sprintf. See ToHclString for details.
 func primitiveToHclString(value interface{}, isNested bool) string {
+	if value == nil {
+		return "null"
+	}
+
 	switch v := value.(type) {
 
 	case bool:

modules/terraform/format_test.go

@@ -18,6 +18,7 @@ func TestFormatTerraformVarsAsArgs(t *testing.T) {
 		{map[string]interface{}{"foo": "bar"}, []string{"-var", "foo=bar"}},
 		{map[string]interface{}{"foo": 123}, []string{"-var", "foo=123"}},
 		{map[string]interface{}{"foo": true}, []string{"-var", "foo=true"}},
+		{map[string]interface{}{"foo": nil}, []string{"-var", "foo=null"}},
 		{map[string]interface{}{"foo": []int{1, 2, 3}}, []string{"-var", "foo=[1, 2, 3]"}},
 		{map[string]interface{}{"foo": map[string]string{"baz": "blah"}}, []string{"-var", "foo={\"baz\" = \"blah\"}"}},
 		{
@@ -45,6 +46,7 @@ func TestPrimitiveToHclString(t *testing.T) {
 		{"true", "true"},
 		{true, "true"},
 		{3, "3"},
+		{nil, "null"},
 		{[]int{1, 2, 3}, "[1 2 3]"}, // Anything that isn't a primitive is forced into a string
 	}
 

modules/terraform/options.go

@@ -9,9 +9,18 @@ import (
 
 // Options for running Terraform commands
 type Options struct {
-	TerraformBinary          string                 // Name of the binary that will be used
-	TerraformDir             string                 // The path to the folder where the Terraform code is defined.
-	Vars                     map[string]interface{} // The vars to pass to Terraform commands using the -var option.
+	TerraformBinary string // Name of the binary that will be used
+	TerraformDir    string // The path to the folder where the Terraform code is defined.
+
+	// The vars to pass to Terraform commands using the -var option. Note that terraform does not support passing `null`
+	// as a variable value through the command line. That is, if you use `map[string]interface{}{"foo": nil}` as `Vars`,
+	// this will translate to the string literal `"null"` being assigned to the variable `foo`. However, nulls in
+	// lists and maps/objects are supported. E.g., the following var will be set as expected (`{ bar = null }`:
+	// map[string]interface{}{
+	//     "foo": map[string]interface{}{"bar": nil},
+	// }
+	Vars map[string]interface{}
+
 	VarFiles                 []string               // The var file paths to pass to Terraform commands using -var-file option.
 	Targets                  []string               // The target resources to pass to the terraform command with -target
 	Lock                     bool                   // The lock option to pass to the terraform command with -lock

test/fixtures/terraform-null/main.tf

@@ -0,0 +1,14 @@
+variable "foo" {
+  type = object({
+    nullable_string    = string
+    nonnullable_string = string
+  })
+}
+
+output "foo" {
+  value = var.foo
+}
+
+output "bar" {
+  value = var.foo.nullable_string == null ? "I AM NULL" : null
+}

test/terraform_unit_null_test.go

@@ -0,0 +1,28 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/gruntwork-io/terratest/modules/terraform"
+	"github.com/magiconair/properties/assert"
+)
+
+func TestUnitNullInput(t *testing.T) {
+	t.Parallel()
+
+	foo := map[string]interface{}{
+		"nullable_string":    nil,
+		"nonnullable_string": "foo",
+	}
+	options := &terraform.Options{
+		TerraformDir: "./fixtures/terraform-null",
+		Vars:         map[string]interface{}{"foo": foo},
+	}
+	terraform.InitAndApply(t, options)
+
+	fooOut := terraform.OutputMap(t, options, "foo")
+	assert.Equal(t, fooOut, map[string]string{"nonnullable_string": "foo", "nullable_string": "<nil>"})
+
+	barOut := terraform.Output(t, options, "bar")
+	assert.Equal(t, barOut, "I AM NULL")
+}