refactor(formatter): no trailing commas in JSON files (#4803)

.changeset/no_more_trailing_commas_in_json_files.md

@@ -0,0 +1,5 @@
+---
+cli: major
+---
+
+# The Biome formatter doesn't add a trailing command in `.json` files, even when `json.formatter.trailingCommas` is set to `true`

crates/biome_cli/tests/commands/format.rs

@@ -2326,7 +2326,7 @@ fn format_json_trailing_commas_all() {
 
     assert!(result.is_ok(), "run_cli returned {result:?}");
 
-    assert_file_contents(&fs, Utf8Path::new(file_path), "{\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n}\n");
+    assert_file_contents(&fs, Utf8Path::new(file_path), "{\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\"\n}\n");
 
     assert_cli_snapshot(SnapshotPayload::new(
         module_path!(),
@@ -2369,7 +2369,7 @@ fn format_json_trailing_commas_overrides_all() {
 
     assert!(result.is_ok(), "run_cli returned {result:?}");
 
-    assert_file_contents(&fs, Utf8Path::new(file_path), "{\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n}\n");
+    assert_file_contents(&fs, Utf8Path::new(file_path), "{\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\",\n\t\"loreum_ipsum_lorem_ipsum\": \"bar\"\n}\n");
 
     assert_cli_snapshot(SnapshotPayload::new(
         module_path!(),

crates/biome_cli/tests/snapshots/main_commands_format/format_json_trailing_commas_all.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
 expression: content
+snapshot_kind: text
 ---
 ## `biome.json`
 
@@ -21,7 +22,7 @@ expression: content
 	"loreum_ipsum_lorem_ipsum": "bar",
 	"loreum_ipsum_lorem_ipsum": "bar",
 	"loreum_ipsum_lorem_ipsum": "bar",
-	"loreum_ipsum_lorem_ipsum": "bar",
+	"loreum_ipsum_lorem_ipsum": "bar"
 }
 
 ```

crates/biome_cli/tests/snapshots/main_commands_format/format_json_trailing_commas_overrides_all.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
 expression: content
+snapshot_kind: text
 ---
 ## `biome.json`
 
@@ -29,7 +30,7 @@ expression: content
 	"loreum_ipsum_lorem_ipsum": "bar",
 	"loreum_ipsum_lorem_ipsum": "bar",
 	"loreum_ipsum_lorem_ipsum": "bar",
-	"loreum_ipsum_lorem_ipsum": "bar",
+	"loreum_ipsum_lorem_ipsum": "bar"
 }
 
 ```

crates/biome_cli/tests/snapshots/main_commands_format/treat_known_json_files_as_jsonc_files.snap

@@ -1,6 +1,7 @@
 ---
 source: crates/biome_cli/tests/snap_test.rs
 expression: content
+snapshot_kind: text
 ---
 ## `files/.babelrc`
 
@@ -45,22 +46,6 @@ format ━━━━━━━━━━━━━━━━━━━━━━━━
 
 # Emitted Messages
 
-```block
-files/.babelrc format ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Formatter would have printed the following content:
-  
-    1   │ - 
-    2   │ - /*test*/·[
-    3   │ - 
-    4   │ - /*·some·other·comment*/1,·2,·3]
-    5   │ - → 
-      1 │ + /*test*/·[/*·some·other·comment*/·1,·2,·3]
-      2 │ + 
-  
-
-```
-
 ```block
 files/.eslintrc.json format ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
@@ -78,22 +63,6 @@ files/.eslintrc.json format ━━━━━━━━━━━━━━━━━
 ```
 
 ```block
-files/.jshintrc format ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-
-  × Formatter would have printed the following content:
-  
-    1   │ - 
-    2   │ - /*test*/·[
-    3   │ - 
-    4   │ - /*·some·other·comment*/1,·2,·3]
-    5   │ - → 
-      1 │ + /*test*/·[/*·some·other·comment*/·1,·2,·3]
-      2 │ + 
-  
-
-```
-
-```block
-Checked 3 files in <TIME>. No fixes applied.
-Found 3 errors.
+Checked 1 file in <TIME>. No fixes applied.
+Found 1 error.
 ```

crates/biome_formatter_test/src/spec.rs

@@ -36,6 +36,9 @@ impl<'a> SpecTestFile<'a> {
         root_path: &'a Utf8Path,
         settings: Option<UpdateSettingsParams>,
     ) -> Option<SpecTestFile<'a>> {
+        if input_file.ends_with("options.json") {
+            return None;
+        }
         let mut console = EnvConsole::default();
         let app = App::with_console(&mut console);
         let file_path = &input_file;

crates/biome_js_formatter/src/context.rs

@@ -130,7 +130,7 @@ impl CstFormatContext for JsFormatContext {
     }
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Default, Clone)]
 pub struct JsFormatOptions {
     /// The indent style.
     indent_style: IndentStyle,

crates/biome_json_formatter/Cargo.toml

@@ -30,6 +30,7 @@ biome_fs             = { path = "../biome_fs" }
 biome_json_parser    = { path = "../biome_json_parser" }
 biome_parser         = { path = "../biome_parser" }
 biome_service        = { path = "../biome_service" }
+biome_test_utils     = { path = "../biome_test_utils" }
 countme              = { workspace = true, features = ["enable"] }
 serde_json           = { workspace = true }
 tests_macros         = { path = "../tests_macros" }

crates/biome_json_formatter/src/context.rs

@@ -7,7 +7,7 @@ use biome_formatter::{
     CstFormatContext, FormatContext, FormatOptions, IndentStyle, LineEnding, LineWidth,
     TransformSourceMap,
 };
-use biome_json_syntax::JsonLanguage;
+use biome_json_syntax::{JsonFileSource, JsonLanguage};
 use std::default::Default;
 use std::fmt;
 use std::rc::Rc;
@@ -67,6 +67,9 @@ pub struct JsonFormatOptions {
     attribute_position: AttributePosition,
     /// Print trailing commas wherever possible in multi-line comma-separated syntactic structures. Defaults to "none".
     trailing_commas: TrailingCommas,
+
+    /// The kind of file
+    file_source: JsonFileSource,
 }
 
 #[derive(Clone, Copy, Debug, Default, Eq, Hash, Deserializable, Merge, PartialEq)]
@@ -78,9 +81,9 @@ pub struct JsonFormatOptions {
 #[cfg_attr(feature = "schema", derive(schemars::JsonSchema))]
 pub enum TrailingCommas {
     #[default]
-    /// The formatter will remove the trailing commas
+    /// The formatter will remove the trailing commas.
     None,
-    /// The trailing commas are allowed and advised
+    /// The trailing commas are allowed and advised only in JSONC files. Trailing commas are removed from JSON files.
     All,
 }
 
@@ -106,8 +109,9 @@ impl fmt::Display for TrailingCommas {
 }
 
 impl JsonFormatOptions {
-    pub fn new() -> Self {
+    pub fn new(file_source: JsonFileSource) -> Self {
         Self {
+            file_source,
             ..Default::default()
         }
     }
@@ -163,6 +167,10 @@ impl JsonFormatOptions {
             TrailingCommas::All => TrailingSeparator::Allowed,
         }
     }
+
+    pub(crate) fn file_source(&self) -> &JsonFileSource {
+        &self.file_source
+    }
 }
 
 impl FormatOptions for JsonFormatOptions {

crates/biome_json_formatter/src/json/lists/array_element_list.rs

@@ -1,7 +1,8 @@
 use crate::prelude::*;
 use crate::separated::FormatAstSeparatedListExtension;
+use biome_formatter::separated::TrailingSeparator;
 use biome_formatter::write;
-use biome_json_syntax::{AnyJsonValue, JsonArrayElementList};
+use biome_json_syntax::{AnyJsonValue, JsonArrayElementList, JsonFileVariant};
 use biome_rowan::{AstNode, AstSeparatedList};
 
 #[derive(Debug, Clone, Default)]
@@ -18,7 +19,12 @@ impl FormatRule<JsonArrayElementList> for FormatJsonArrayElementList {
 
         match layout {
             ArrayLayout::Fill => {
-                let trailing_separator = f.options().to_trailing_separator();
+                let file_source = f.options().file_source();
+                let trailing_separator = if file_source.variant() == JsonFileVariant::Standard {
+                    TrailingSeparator::Omit
+                } else {
+                    f.options().to_trailing_separator()
+                };
                 let mut filler = f.fill();
 
                 for (element, formatted) in node
@@ -41,7 +47,12 @@ impl FormatRule<JsonArrayElementList> for FormatJsonArrayElementList {
             }
 
             ArrayLayout::OnePerLine => {
-                let trailing_separator = f.options().to_trailing_separator();
+                let file_source = f.options().file_source();
+                let trailing_separator = if file_source.variant() == JsonFileVariant::Standard {
+                    TrailingSeparator::Omit
+                } else {
+                    f.options().to_trailing_separator()
+                };
                 let mut join = f.join_nodes_with_soft_line();
 
                 for (element, formatted) in node

crates/biome_json_formatter/src/json/lists/member_list.rs

@@ -1,6 +1,7 @@
 use crate::prelude::*;
 use crate::separated::FormatAstSeparatedListExtension;
-use biome_json_syntax::JsonMemberList;
+use biome_formatter::separated::TrailingSeparator;
+use biome_json_syntax::{JsonFileVariant, JsonMemberList};
 use biome_rowan::{AstNode, AstSeparatedList};
 
 #[derive(Debug, Clone, Default)]
@@ -9,7 +10,12 @@ pub(crate) struct FormatJsonMemberList;
 impl FormatRule<JsonMemberList> for FormatJsonMemberList {
     type Context = JsonFormatContext;
     fn fmt(&self, node: &JsonMemberList, f: &mut JsonFormatter) -> FormatResult<()> {
-        let trailing_separator = f.options().to_trailing_separator();
+        let file_source = f.options().file_source();
+        let trailing_separator = if file_source.variant() == JsonFileVariant::Standard {
+            TrailingSeparator::Omit
+        } else {
+            f.options().to_trailing_separator()
+        };
         let mut join = f.join_nodes_with_soft_line();
 
         for (element, formatted) in node

crates/biome_json_formatter/tests/spec_test.rs

@@ -1,5 +1,7 @@
 use biome_formatter_test::spec::{SpecSnapshot, SpecTestFile};
-use biome_json_formatter::{context::JsonFormatOptions, JsonFormatLanguage};
+use biome_json_formatter::JsonFormatLanguage;
+use biome_json_syntax::JsonLanguage;
+use biome_test_utils::create_formatting_options;
 use camino::Utf8Path;
 
 mod language {
@@ -29,8 +31,11 @@ pub fn run(spec_input_file: &str, _expected_file: &str, test_directory: &str, _f
     let Some(test_file) = SpecTestFile::try_from_file(spec_input_file, root_path, None) else {
         return;
     };
+    let mut diagnostics = vec![];
+
+    let options =
+        create_formatting_options::<JsonLanguage>(test_file.input_file(), &mut diagnostics);
 
-    let options = JsonFormatOptions::default();
     let language = language::JsonTestFormatLanguage::default();
 
     let snapshot = SpecSnapshot::new(

crates/biome_json_formatter/tests/spec_tests.rs

@@ -4,6 +4,6 @@ mod spec_test;
 mod formatter {
 
     mod json_module {
-        tests_macros::gen_tests! {"tests/specs/json/**/*.json", crate::spec_test::run, ""}
+        tests_macros::gen_tests! {"tests/specs/json/**/*.{json,jsonc}", crate::spec_test::run, ""}
     }
 }

crates/biome_json_formatter/tests/specs/json/trailing_comma_never/classic.json

@@ -0,0 +1,7 @@
+{
+  "list": [],
+  "list1": [],
+  "list2": [],
+  "list3": [],
+  "list4": []
+}

crates/biome_json_formatter/tests/specs/json/trailing_comma_never/classic.json.snap

@@ -0,0 +1,62 @@
+---
+source: crates/biome_formatter_test/src/snapshot_builder.rs
+info: json/trailing_comma_never/classic.json
+snapshot_kind: text
+---
+# Input
+
+```json
+{
+  "list": [],
+  "list1": [],
+  "list2": [],
+  "list3": [],
+  "list4": []
+}
+
+```
+
+
+=============================
+
+# Outputs
+
+## Output 1
+
+-----
+Indent style: Tab
+Indent width: 2
+Line ending: LF
+Line width: 80
+Trailing commas: None
+-----
+
+```json
+{
+	"list": [],
+	"list1": [],
+	"list2": [],
+	"list3": [],
+	"list4": []
+}
+```
+
+## Output 1
+
+-----
+Indent style: Tab
+Indent width: 2
+Line ending: LF
+Line width: 80
+Trailing commas: All
+-----
+
+```json
+{
+	"list": [],
+	"list1": [],
+	"list2": [],
+	"list3": [],
+	"list4": []
+}
+```

crates/biome_json_formatter/tests/specs/json/trailing_comma_never/classic.jsonc

@@ -0,0 +1,7 @@
+{
+	"list": [],
+	"list1": [],
+	"list2": [],
+	"list3": [],
+	"list4": [],
+}