Add fmt test to make sure formatting works for all parser test cases

crates/compiler/fmt/src/collection.rs

@@ -8,6 +8,7 @@ use crate::{
 
 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
 pub enum Braces {
+    Round,
     Square,
     Curly,
 }
@@ -22,11 +23,13 @@ pub fn fmt_collection<'a, 'buf, T: ExtractSpaces<'a> + Formattable>(
     <T as ExtractSpaces<'a>>::Item: Formattable,
 {
     let start = match braces {
+        Braces::Round => '(',
         Braces::Curly => '{',
         Braces::Square => '[',
     };
 
     let end = match braces {
+        Braces::Round => ')',
         Braces::Curly => '}',
         Braces::Square => ']',
     };

crates/compiler/fmt/src/def.rs

@@ -134,7 +134,7 @@ impl<'a> Formattable for TypeDef<'a> {
 
                 if !self.is_multiline() {
                     debug_assert_eq!(members.len(), 1);
-                    buf.push_str(" ");
+                    buf.spaces(1);
                     members[0].format_with_options(
                         buf,
                         Parens::NotNeeded,

crates/compiler/fmt/src/expr.rs

@@ -326,9 +326,6 @@ impl<'a> Formattable for Expr<'a> {
             Record(fields) => {
                 fmt_record(buf, None, *fields, indent);
             }
-            Tuple(_fields) => {
-                todo!("format tuple");
-            }
             RecordUpdate { update, fields } => {
                 fmt_record(buf, Some(*update), *fields, indent);
             }
@@ -386,6 +383,7 @@ impl<'a> Formattable for Expr<'a> {
                 fmt_if(buf, branches, final_else, self.is_multiline(), indent);
             }
             When(loc_condition, branches) => fmt_when(buf, loc_condition, branches, indent),
+            Tuple(items) => fmt_collection(buf, indent, Braces::Round, *items, Newlines::No),
             List(items) => fmt_collection(buf, indent, Braces::Square, *items, Newlines::No),
             BinOps(lefts, right) => fmt_binops(buf, lefts, right, false, parens, indent),
             UnaryOp(sub_expr, unary_op) => {
@@ -421,7 +419,10 @@ impl<'a> Formattable for Expr<'a> {
                 buf.push('.');
                 buf.push_str(key);
             }
-            MalformedIdent(_, _) => {}
+            MalformedIdent(str, _) => {
+                buf.indent(indent);
+                buf.push_str(str)
+            }
             MalformedClosure => {}
             PrecedenceConflict { .. } => {}
         }
@@ -505,10 +506,10 @@ fn push_op(buf: &mut Buf, op: BinOp) {
 pub fn fmt_str_literal<'buf>(buf: &mut Buf<'buf>, literal: StrLiteral, indent: u16) {
     use roc_parse::ast::StrLiteral::*;
 
-    buf.indent(indent);
-    buf.push('"');
     match literal {
         PlainLine(string) => {
+            buf.indent(indent);
+            buf.push('"');
             // When a PlainLine contains '\n' or '"', format as a block string
             if string.contains('"') || string.contains('\n') {
                 buf.push_str("\"\"");
@@ -523,15 +524,21 @@ pub fn fmt_str_literal<'buf>(buf: &mut Buf<'buf>, literal: StrLiteral, indent: u
             } else {
                 buf.push_str_allow_spaces(string);
             };
+            buf.push('"');
         }
         Line(segments) => {
+            buf.indent(indent);
+            buf.push('"');
             for seg in segments.iter() {
                 format_str_segment(seg, buf, 0)
             }
+            buf.push('"');
         }
         Block(lines) => {
             // Block strings will always be formatted with """ on new lines
-            buf.push_str("\"\"");
+            buf.ensure_ends_with_newline();
+            buf.indent(indent);
+            buf.push_str("\"\"\"");
             buf.newline();
 
             for segments in lines.iter() {
@@ -543,10 +550,9 @@ pub fn fmt_str_literal<'buf>(buf: &mut Buf<'buf>, literal: StrLiteral, indent: u
                 buf.newline();
             }
             buf.indent(indent);
-            buf.push_str("\"\"");
+            buf.push_str("\"\"\"");
         }
     }
-    buf.push('"');
 }
 
 fn fmt_binops<'a, 'buf>(

crates/compiler/fmt/src/lib.rs

@@ -109,7 +109,7 @@ impl<'a> Buf<'a> {
         if self.spaces_to_flush > 0 {
             self.flush_spaces();
             self.newline();
-        } else if !self.text.ends_with('\n') {
+        } else if !self.text.ends_with('\n') && !self.text.is_empty() {
             self.newline()
         }
     }