fix: Decor in DocumentMut no longer ignored

crates/toml_edit/src/encode.rs

@@ -6,7 +6,9 @@ use toml_datetime::Datetime;
 use crate::inline_table::DEFAULT_INLINE_KEY_DECOR;
 use crate::key::Key;
 use crate::repr::{Formatted, Repr, ValueRepr};
-use crate::table::{DEFAULT_KEY_DECOR, DEFAULT_KEY_PATH_DECOR, DEFAULT_TABLE_DECOR};
+use crate::table::{
+    DEFAULT_KEY_DECOR, DEFAULT_KEY_PATH_DECOR, DEFAULT_ROOT_DECOR, DEFAULT_TABLE_DECOR,
+};
 use crate::value::{
     DEFAULT_LEADING_VALUE_DECOR, DEFAULT_TRAILING_VALUE_DECOR, DEFAULT_VALUE_DECOR,
 };
@@ -197,6 +199,9 @@ pub(crate) fn encode_value(
 
 impl Display for DocumentMut {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        let decor = self.decor();
+        decor.prefix_encode(f, None, DEFAULT_ROOT_DECOR.0)?;
+
         let mut path = Vec::new();
         let mut last_position = 0;
         let mut tables = Vec::new();
@@ -214,6 +219,7 @@ impl Display for DocumentMut {
         for (_, table, path, is_array) in tables {
             visit_table(f, None, table, &path, is_array, &mut first_table)?;
         }
+        decor.suffix_encode(f, None, DEFAULT_ROOT_DECOR.1)?;
         self.trailing().encode_with_default(f, None, "")
     }
 }

crates/toml_edit/src/table.rs

@@ -504,6 +504,7 @@ fn decorate_table(table: &mut Table) {
 }
 
 // `key1 = value1`
+pub(crate) const DEFAULT_ROOT_DECOR: (&str, &str) = ("", "");
 pub(crate) const DEFAULT_KEY_DECOR: (&str, &str) = ("", " ");
 pub(crate) const DEFAULT_TABLE_DECOR: (&str, &str) = ("\n", "");
 pub(crate) const DEFAULT_KEY_PATH_DECOR: (&str, &str) = ("", "");

crates/toml_edit/tests/testsuite/edit.rs

@@ -41,6 +41,15 @@ impl Test {
         }
         self
     }
+    fn running_on_doc<F>(&mut self, func: F) -> &mut Self
+    where
+        F: Fn(&mut DocumentMut),
+    {
+        {
+            func(&mut self.doc);
+        }
+        self
+    }
 
     #[track_caller]
     fn produces_display(&self, expected: snapbox::data::Inline) -> &Self {
@@ -49,6 +58,97 @@ impl Test {
     }
 }
 
+#[test]
+fn test_add_root_decor() {
+    given(
+        r#"[package]
+name = "hello"
+version = "1.0.0"
+
+[[bin]]
+name = "world"
+path = "src/bin/world/main.rs"
+
+[dependencies]
+nom = "4.0" # future is here
+
+[[bin]]
+name = "delete me please"
+path = "src/bin/dmp/main.rs""#,
+    )
+    .running_on_doc(|document| {
+        document.decor_mut().set_prefix("# Some Header\n\n");
+        document.decor_mut().set_suffix("# Some Footer");
+        document.set_trailing("\n\ntrailing...");
+    })
+    .produces_display(str![[r#"
+# Some Header
+
+[package]
+name = "hello"
+version = "1.0.0"
+
+[[bin]]
+name = "world"
+path = "src/bin/world/main.rs"
+
+[dependencies]
+nom = "4.0" # future is here
+
+[[bin]]
+name = "delete me please"
+path = "src/bin/dmp/main.rs"
+# Some Footer
+
+trailing...
+"#]]);
+}
+
+/// Tests that default decor is None for both suffix and prefix and that this means empty strings
+#[test]
+fn test_no_root_decor() {
+    given(
+        r#"[package]
+name = "hello"
+version = "1.0.0"
+
+[[bin]]
+name = "world"
+path = "src/bin/world/main.rs"
+
+[dependencies]
+nom = "4.0" # future is here
+
+[[bin]]
+name = "delete me please"
+path = "src/bin/dmp/main.rs""#,
+    )
+    .running_on_doc(|document| {
+        assert!(document.decor().prefix().is_none());
+        assert!(document.decor().suffix().is_none());
+        document.set_trailing("\n\ntrailing...");
+    })
+    .produces_display(str![[r#"
+[package]
+name = "hello"
+version = "1.0.0"
+
+[[bin]]
+name = "world"
+path = "src/bin/world/main.rs"
+
+[dependencies]
+nom = "4.0" # future is here
+
+[[bin]]
+name = "delete me please"
+path = "src/bin/dmp/main.rs"
+
+
+trailing...
+"#]]);
+}
+
 // insertion
 
 #[test]