Should return an error if the provider kv pair is not in the metadata file

post-processor/vagrant-cloud/post-processor_test.go

@@ -327,6 +327,26 @@ func TestProviderFromVagrantBox_metadata_bad_json(t *testing.T) {
 	t.Logf("%s", err)
 }
 
+func TestProviderFromVagrantBox_metadata_no_provider_key(t *testing.T) {
+	// Bad: Create a box with no 'provider' key in the metadata.json file
+	files := tarFiles{
+		{"foo.txt", "This is a foo file"},
+		{"bar.txt", "This is a bar file"},
+		{"metadata.json", `{"cows":"moo"}`},
+	}
+	boxfile, err := createBox(files)
+	if err != nil {
+		t.Fatalf("Error creating test box: %s", err)
+	}
+	defer os.Remove(boxfile.Name())
+
+	_, err = providerFromVagrantBox(boxfile.Name())
+	if err == nil {
+		t.Fatalf("Should have error as box files metadata.json file is empty")
+	}
+	t.Logf("%s", err)
+}
+
 func TestProviderFromVagrantBox_metadata_provider_value_empty(t *testing.T) {
 	// Bad: The boxes metadata.json file 'provider' key has an empty value
 	files := tarFiles{