diff --git a/src/toml.rs b/src/toml.rs
index 95da2ae..6fbb000 100644
--- a/src/toml.rs
+++ b/src/toml.rs
@@ -255,7 +255,6 @@ mod tests {
     fn no_comments() {
         let out = format::<test_utils::example1::Conf>(FormatOptions {
             comments: false,
-            indent: 0,
             .. FormatOptions::default()
         });
         assert_str_eq!(&out, include_format_output!("1-no-comments.toml"));
diff --git a/src/yaml.rs b/src/yaml.rs
index 5b8dab9..eb3a15a 100644
--- a/src/yaml.rs
+++ b/src/yaml.rs
@@ -229,3 +229,26 @@ impl fmt::Display for PrintExpr {
         }
     }
 }
+
+
+#[cfg(test)]
+mod tests {
+    use crate::test_utils::{self, include_format_output};
+    use super::{format, FormatOptions};
+    use pretty_assertions::assert_str_eq;
+
+    #[test]
+    fn default() {
+        let out = format::<test_utils::example1::Conf>(FormatOptions::default());
+        assert_str_eq!(&out, include_format_output!("1-default.yaml"));
+    }
+
+    #[test]
+    fn no_comments() {
+        let out = format::<test_utils::example1::Conf>(FormatOptions {
+            comments: false,
+            .. FormatOptions::default()
+        });
+        assert_str_eq!(&out, include_format_output!("1-no-comments.yaml"));
+    }
+}
diff --git a/tests/format-output/1-default.yaml b/tests/format-output/1-default.yaml
new file mode 100644
index 0000000..d3e17ec
--- /dev/null
+++ b/tests/format-output/1-default.yaml
@@ -0,0 +1,43 @@
+# A sample configuration for our app.
+
+# Name of the website.
+#
+# Required! This value must be specified.
+#site_name:
+
+# Configurations related to the HTTP communication.
+http:
+  # The port the server will listen on.
+  #
+  # Can also be specified via environment variable `PORT`.
+  #
+  # Required! This value must be specified.
+  #port:
+
+  headers:
+    # The header in which the reverse proxy specifies the username.
+    #
+    # Default value: x-username
+    #username: x-username
+
+    # The header in which the reverse proxy specifies the display name.
+    #
+    # Default value: x-display-name
+    #display_name: x-display-name
+
+  # The bind address of the server. Can be set to `0.0.0.0` for example, to
+  # allow other users of the network to access the server.
+  #
+  # Default value: 127.0.0.1
+  #bind: 127.0.0.1
+
+# Configuring the logging.
+log:
+  # If set to `true`, the app will log to stdout.
+  #
+  # Default value: true
+  #stdout: true
+
+  # If this is set, the app will write logs to the given file. Of course,
+  # the app has to have write access to that file.
+  #file:
diff --git a/tests/format-output/1-no-comments.yaml b/tests/format-output/1-no-comments.yaml
new file mode 100644
index 0000000..d2952aa
--- /dev/null
+++ b/tests/format-output/1-no-comments.yaml
@@ -0,0 +1,10 @@
+#site_name:
+http:
+  #port:
+  headers:
+    #username: x-username
+    #display_name: x-display-name
+  #bind: 127.0.0.1
+log:
+  #stdout: true
+  #file: