Do not read temporary editor files, fixes #548

This fixes a bug where Terraform would error with the following:

```
Error loading config: Error reading
/Users/rhenrichs/work/example/.#example.tf: open
/Users/rhenrichs/work/example/.#example.tf: no such file or directory
```

The solution implemented here ignores the common emacs and vim
temporary file formats.

Note: the potential danger with merging this is that Terraform could
quickly have requests to ignore other file formats.

config/loader.go

@@ -162,7 +162,7 @@ func dirFiles(dir string) ([]string, []string, error) {
 			// Only care about files that are valid to load
 			name := fi.Name()
 			extValue := ext(name)
-			if extValue == "" {
+			if extValue == "" || isTemporaryFile(name) {
 				continue
 			}
 
@@ -182,3 +182,12 @@ func dirFiles(dir string) ([]string, []string, error) {
 
 	return files, overrides, nil
 }
+
+// isTemporaryFile returns true or false depending on whether the
+// provided file name is a temporary file for the following editors:
+// emacs or vim.
+func isTemporaryFile(name string) bool {
+	return strings.HasSuffix(name, "~") || // vim
+		strings.HasPrefix(name, ".#") || // emacs
+		(strings.HasPrefix(name, "#") && strings.HasSuffix(name, "#")) // emacs
+}

config/loader_test.go

@@ -383,6 +383,13 @@ func TestLoad_createBeforeDestroy(t *testing.T) {
 	}
 }
 
+func TestLoad_temporary_files(t *testing.T) {
+	_, err := LoadDir(filepath.Join(fixtureDir, "dir-temporary-files"))
+	if err == nil {
+		t.Fatalf("Expected to see an error stating no config files found")
+	}
+}
+
 const basicOutputsStr = `
 web_ip
   vars

config/test-fixtures/dir-temporary-files/#emacs-two.tf#

@@ -0,0 +1,20 @@
+provider "do" {
+  api_key = "${var.foo}"
+}
+
+resource "aws_security_group" "firewall" {
+    count = 5
+}
+
+resource aws_instance "web" {
+    ami = "${var.foo}"
+    security_groups = [
+        "foo",
+        "${aws_security_group.firewall.foo}"
+    ]
+
+    network_interface {
+        device_index = 0
+        description = "Main network interface"
+    }
+}

config/test-fixtures/dir-temporary-files/.#emacs-one.tf

@@ -0,0 +1,17 @@
+variable "foo" {
+    default = "bar"
+    description = "bar"
+}
+
+provider "aws" {
+  access_key = "foo"
+  secret_key = "bar"
+}
+
+resource "aws_instance" "db" {
+    security_groups = "${aws_security_group.firewall.*.id}"
+}
+
+output "web_ip" {
+    value = "${aws_instance.web.private_ip}"
+}

config/test-fixtures/dir-temporary-files/vim-one.tf~

@@ -0,0 +1,17 @@
+variable "foo" {
+    default = "bar"
+    description = "bar"
+}
+
+provider "aws" {
+  access_key = "foo"
+  secret_key = "bar"
+}
+
+resource "aws_instance" "db" {
+    security_groups = "${aws_security_group.firewall.*.id}"
+}
+
+output "web_ip" {
+    value = "${aws_instance.web.private_ip}"
+}