fix error when writing file with empty content

go.mod

@@ -4,3 +4,5 @@ require (
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/hashicorp/terraform-plugin-sdk v1.0.0
 )
+
+go 1.13

local/data_source_local_file.go

@@ -1,9 +1,7 @@
 package local
 
 import (
-	"crypto/sha1"
 	"encoding/base64"
-	"encoding/hex"
 	"io/ioutil"
 
 	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
@@ -42,8 +40,7 @@ func dataSourceLocalFileRead(d *schema.ResourceData, _ interface{}) error {
 	d.Set("content", string(content))
 	d.Set("content_base64", base64.StdEncoding.EncodeToString(content))
 
-	checksum := sha1.Sum([]byte(content))
-	d.SetId(hex.EncodeToString(checksum[:]))
+	d.SetId("-")
 
 	return nil
 }

local/resource_local_file.go

@@ -1,9 +1,8 @@
 package local
 
 import (
-	"crypto/sha1"
+	"bytes"
 	"encoding/base64"
-	"encoding/hex"
 	"io/ioutil"
 	"os"
 	"path"
@@ -14,9 +13,10 @@ import (
 
 func resourceLocalFile() *schema.Resource {
 	return &schema.Resource{
-		Create: resourceLocalFileCreate,
+		Create: resourceLocalFileCreateUpdate,
 		Read:   resourceLocalFileRead,
 		Delete: resourceLocalFileDelete,
+		Update: resourceLocalFileCreateUpdate,
 
 		Schema: map[string]*schema.Schema{
 			"content": {
@@ -28,7 +28,6 @@ func resourceLocalFile() *schema.Resource {
 			"sensitive_content": {
 				Type:          schema.TypeString,
 				Optional:      true,
-				ForceNew:      true,
 				Sensitive:     true,
 				ConflictsWith: []string{"content", "content_base64"},
 			},
@@ -80,8 +79,12 @@ func resourceLocalFileRead(d *schema.ResourceData, _ interface{}) error {
 		return err
 	}
 
-	outputChecksum := sha1.Sum([]byte(outputContent))
-	if hex.EncodeToString(outputChecksum[:]) != d.Id() {
+	content, err := resourceLocalFileContent(d)
+	if err != nil {
+		return err
+	}
+
+	if !bytes.Equal(outputContent, content) {
 		d.SetId("")
 		return nil
 	}
@@ -101,12 +104,11 @@ func resourceLocalFileContent(d *schema.ResourceData) ([]byte, error) {
 	return []byte(content.(string)), nil
 }
 
-func resourceLocalFileCreate(d *schema.ResourceData, _ interface{}) error {
+func resourceLocalFileCreateUpdate(d *schema.ResourceData, _ interface{}) error {
 	content, err := resourceLocalFileContent(d)
 	if err != nil {
 		return err
 	}
-
 	destination := d.Get("filename").(string)
 
 	destinationDir := path.Dir(destination)
@@ -126,8 +128,7 @@ func resourceLocalFileCreate(d *schema.ResourceData, _ interface{}) error {
 		return err
 	}
 
-	checksum := sha1.Sum([]byte(content))
-	d.SetId(hex.EncodeToString(checksum[:]))
+	d.SetId("-")
 
 	return nil
 }

local/resource_local_file_test.go

@@ -152,5 +152,57 @@ resource "local_file" "file" {
 	})
 
 	defer os.Remove(destinationDirPath)
+}
+
+func TestLocalFile_EmptyContent(t *testing.T) {
+	var cases = []struct {
+		path    string
+		content string
+		config  string
+	}{
+		{
+			"local_file",
+			"This is some content",
+			`resource "local_file" "file" {
+         content     = "This is some content"
+         filename    = "local_file"
+      }`,
+		},
+		{
+			"local_file",
+			"",
+			`resource "local_file" "file" {
+         content     = ""
+         filename    = "local_file"
+      }`,
+		},
+	}
 
+	for _, tt := range cases {
+		r.UnitTest(t, r.TestCase{
+			Providers: testProviders,
+			Steps: []r.TestStep{
+				{
+					Config: tt.config,
+					Check: func(s *terraform.State) error {
+						content, err := ioutil.ReadFile(tt.path)
+						if err != nil {
+							return fmt.Errorf("config:\n%s\n,got: %s\n", tt.config, err)
+						}
+						if string(content) != tt.content {
+							return fmt.Errorf("config:\n%s\ngot:\n%s\nwant:\n%s\n", tt.config, content, tt.content)
+						}
+						return nil
+					},
+					Destroy: false,
+				},
+			},
+			CheckDestroy: func(*terraform.State) error {
+				if _, err := os.Stat(tt.path); os.IsNotExist(err) {
+					return nil
+				}
+				return errors.New("local_file did not get destroyed")
+			},
+		})
+	}
 }