Add a test for dotenv output ordering

stores/dotenv/store_test.go

@@ -63,3 +63,20 @@ func TestEmitValueNonstring(t *testing.T) {
 	_, err := (&Store{}).EmitValue(BRANCH)
 	assert.NotNil(t, err)
 }
+
+func TestEmitEncryptedFileStability(t *testing.T) {
+	// emit the same tree multiple times to ensure the output is stable
+	// i.e. emitting the same tree always yields exactly the same output
+	var previous []byte
+	for i := 0; i < 10; i += 1 {
+		bytes, err := (&Store{}).EmitEncryptedFile(sops.Tree{
+			Branches: []sops.TreeBranch{{}},
+		})
+		assert.Nil(t, err)
+		assert.NotEmpty(t, bytes)
+		if previous != nil {
+			assert.Equal(t, previous, bytes)
+		}
+		previous = bytes
+	}
+}