test: custom tests for formatter

CONTRIBUTING.md

@@ -198,19 +198,23 @@ The command will tell the test suite to generate and update the `.rast` files.
 If tests that are inside the `ok/` folder fail or if tests that are inside the `err/`
 folder don't emit, the whole test suite will fail.
 
-### Write snapshot tests for the formatter
+
+### Write tests for the formatter
 
 We use [insta.rs](https://insta.rs/docs) for our snapshot tests, please make sure you read its documentation to learn the basics of snapshot testing.
 You should install the companion [`cargo-insta`](https://insta.rs/docs/cli/) command to assist with snapshot reviewing.
 
-To create a new snapshot test for JavaScript, create a new file to `crates/rome_formatter/tests/specs/javascript`, e.g. `arrow.js`
+To create a new snapshot test for JavaScript, create a new file to `crates/rome_formatter/tests/specs/js/`, e.g. `arrow_with_spaces.js`
 
 ```javascript
-const foo = () => {
+const foo     = ()    => {
 	return bar
 }
 ```
 
+Files processed as modules must go inside the `module/` directory, files processed as script must go inside the 
+`script/` directory.
+
 Run the following command to generate the new snapshot (the snapshot tests are generated by a procedure macro so we need to recompile the tests):
 
 ```bash
@@ -226,3 +230,24 @@ cargo watch -i '*.new' -x 'test -p rome_formatter formatter'
 After test execution, you will get a new `arrow.js.snap.new` file.
 
 To actually update the snapshot, run `cargo insta review` to interactively review and accept the pending snapshot. `arrow.js.snap.new` will be replaced with `arrow.js.snap`
+
+Sometimes, you need to verify the formatting for different cases/options. In order to do that, create a folder with 
+the cases you need to verify. If we needed to follow the previous example: 
+
+1. create a folder called `arrow_with_spaces/` and move the JS file there;
+2. then create a file called `options.json`
+3. The content would be something like:
+    ```json
+    {
+        "cases": [
+            {
+                "line_width": 120,
+                "indent_style": {"Space": 4}
+            }
+        ]
+    }
+    ````
+4. the `cases` keyword is mandatory;
+5. then each object of the array will contain the matrix of options you'd want to test. 
+In this case the test suite will run a **second test case** with `line_width` to 120 and `ident_style` with  4 spaces
+6. when the test suite is run, you will have two outputs in your snapshot: the default one and the custom one

crates/rome_formatter/Cargo.toml

@@ -14,5 +14,7 @@ cfg-if = "1.0.0"
 thiserror = "1.0.30"
 
 [dev-dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
 tests_macros = { path = "../tests_macros" }
 insta = "1.10.0"

crates/rome_formatter/src/lib.rs

@@ -55,11 +55,13 @@ pub mod formatter_traits;
 mod intersperse;
 mod printer;
 mod ts;
+
 pub use formatter::Formatter;
 use rome_rowan::TextRange;
 use rome_rowan::TextSize;
 use rome_rowan::TokenAtOffset;
 use rslint_parser::{parse, Syntax, SyntaxError, SyntaxNode};
+use std::fmt::Display;
 
 pub use format_element::{
     block_indent, concat_elements, empty_element, empty_line, group_elements, hard_line_break,
@@ -141,6 +143,15 @@ impl FromStr for IndentStyle {
     }
 }
 
+impl Display for IndentStyle {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            IndentStyle::Tab => write!(f, "Tab"),
+            IndentStyle::Space(size) => write!(f, "Spaces, size: {}", size),
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy)]
 pub struct FormatOptions {
     /// The indent style
@@ -168,6 +179,14 @@ impl Default for FormatOptions {
     }
 }
 
+impl Display for FormatOptions {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        writeln!(f, "Indent style: {}", self.indent_style)?;
+        writeln!(f, "Line width: {}", self.line_width)?;
+        Ok(())
+    }
+}
+
 /// Lightweight sourcemap marker between source and output tokens
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct SourceMarker {

crates/rome_formatter/tests/spec_test.rs

@@ -1,9 +1,90 @@
 use rome_core::App;
-use rome_formatter::{format, FormatOptions};
+use rome_formatter::{format, FormatOptions, IndentStyle};
 use rome_path::RomePath;
 use rslint_parser::{parse, Syntax};
+use serde::{Deserialize, Serialize};
+use std::fmt::Debug;
 use std::fs;
-use std::path::Path;
+use std::path::{Path, PathBuf};
+
+#[derive(Debug, Eq, PartialEq, Clone, Copy, Deserialize, Serialize)]
+pub enum SerializableIndentStyle {
+    /// Tab
+    Tab,
+    /// Space, with its quantity
+    Space(u8),
+}
+
+impl From<SerializableIndentStyle> for IndentStyle {
+    fn from(test: SerializableIndentStyle) -> Self {
+        match test {
+            SerializableIndentStyle::Tab => IndentStyle::Tab,
+            SerializableIndentStyle::Space(s) => IndentStyle::Space(s),
+        }
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize, Clone)]
+pub struct SerializableFormatOptions {
+    /// The indent style
+    pub indent_style: Option<SerializableIndentStyle>,
+
+    /// What's the max width of a line. Defaults to 80
+    pub line_width: Option<u16>,
+}
+
+impl From<SerializableFormatOptions> for FormatOptions {
+    fn from(test: SerializableFormatOptions) -> Self {
+        Self {
+            indent_style: test
+                .indent_style
+                .map_or_else(|| IndentStyle::Tab, |value| value.into()),
+            line_width: test.line_width.unwrap_or(80),
+        }
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub struct TestOptions {
+    cases: Vec<SerializableFormatOptions>,
+}
+
+#[derive(Debug, Default)]
+struct SnapshotContent {
+    input: String,
+    output: Vec<(String, FormatOptions)>,
+}
+
+impl SnapshotContent {
+    pub fn add_output(&mut self, content: &str, options: FormatOptions) {
+        self.output.push((String::from(content), options))
+    }
+
+    pub fn set_input(&mut self, content: &str) {
+        self.input = String::from(content);
+    }
+
+    pub fn snap_content(&mut self) -> String {
+        let mut output = String::new();
+        output.push_str("# Input");
+        output.push('\n');
+        output.push_str(self.input.as_str());
+        output.push_str("\n=============================\n");
+
+        output.push_str("# Outputs\n");
+        let iter = self.output.iter();
+        for (index, (content, options)) in iter.enumerate() {
+            let formal_index = index + 1;
+            output.push_str(format!("## Output {formal_index}\n").as_str());
+            output.push_str("-----\n");
+            output.push_str(format!("{}", options).as_str());
+            output.push_str("-----\n");
+            output.push_str(content.as_str());
+        }
+
+        output
+    }
+}
 
 /// [insta.rs](https://insta.rs/docs) snapshot testing
 ///
@@ -22,7 +103,7 @@ use std::path::Path;
 ///
 /// * `json/null` -> input: `tests/specs/json/null.json`, expected output: `tests/specs/json/null.json.snap`
 /// * `null` -> input: `tests/specs/null.json`, expected output: `tests/specs/null.json.snap`
-pub fn run(spec_input_file: &str, _: &str, file_type: &str) {
+pub fn run(spec_input_file: &str, _expected_file: &str, test_directory: &str, file_type: &str) {
     let app = App::new();
     let file_path = &spec_input_file;
     let spec_input_file = Path::new(spec_input_file);
@@ -35,26 +116,47 @@ pub fn run(spec_input_file: &str, _: &str, file_type: &str) {
 
     let mut rome_path = RomePath::new(file_path);
     if app.can_format(&rome_path) {
+        let mut snapshot_content = SnapshotContent::default();
         let buffer = rome_path.get_buffer_from_file();
         let syntax = if file_type == "module" {
             Syntax::default().module()
         } else {
             Syntax::default()
         };
 
+        let input = fs::read_to_string(file_path).unwrap();
+        snapshot_content.set_input(input.as_str());
+
         let root = parse(buffer.as_str(), 0, syntax).syntax();
         let formatted_result = format(FormatOptions::default(), &root);
         let file_name = spec_input_file.file_name().unwrap().to_str().unwrap();
-        let input = fs::read_to_string(file_path).unwrap();
-        let result = formatted_result.unwrap();
         // we ignore the error for now
-        let snapshot = format!("# Input\n{}\n---\n# Output\n{}", input, result.as_code());
+        let result = formatted_result.unwrap();
+
+        snapshot_content.add_output(result.as_code(), FormatOptions::default());
+
+        let test_directory = PathBuf::from(test_directory);
+        let options_path = test_directory.join("options.json");
+        if options_path.exists() {
+            {
+                let mut options_path = RomePath::new(options_path.display().to_string().as_str());
+                // SAFETY: we checked its existence already, we assume we have rights to read it
+                let options: TestOptions =
+                    serde_json::from_str(options_path.get_buffer_from_file().as_str()).unwrap();
+
+                for test_case in options.cases {
+                    let options = test_case.clone();
+                    let formatted_result = format(test_case.into(), &root).unwrap();
+                    snapshot_content.add_output(formatted_result.as_code(), options.into());
+                }
+            }
+        }
 
         insta::with_settings!({
             prepend_module_to_snapshot => false,
             snapshot_path => spec_input_file.parent().unwrap(),
         }, {
-            insta::assert_snapshot!(file_name, snapshot, file_name);
+            insta::assert_snapshot!(file_name, snapshot_content.snap_content(), file_name);
         });
     }
 }

crates/rome_formatter/tests/spec_tests.rs

@@ -4,11 +4,11 @@ mod formatter {
 
     mod js_module {
         use crate::spec_test;
-        tests_macros::gen_tests! {"tests/specs/js/module/**/**/*.js", spec_test::run, "module"}
+        tests_macros::gen_tests! {"tests/specs/js/module/**/**/**/*.js", spec_test::run, "module"}
     }
 
     mod js_script {
         use crate::spec_test;
-        tests_macros::gen_tests! {"tests/specs/js/script/**/**/*.js", spec_test::run, "script"}
+        tests_macros::gen_tests! {"tests/specs/js/script/**/**/**/*.js", spec_test::run, "script"}
     }
 }

crates/rome_formatter/tests/specs/js/module/array/array_nested.js.snap

@@ -1,5 +1,6 @@
 ---
 source: crates/rome_formatter/tests/spec_test.rs
+assertion_line: 157
 expression: array_nested.js
 
 ---
@@ -46,8 +47,13 @@ let m1 = [{ a, b }, { a }, { a }];
 let n1 = [{ a, b }, { a, b }];
 let o1 = [{ a, b }, { a, b, c }];
 
----
-# Output
+=============================
+# Outputs
+## Output 1
+-----
+Indent style: Tab
+Line width: 80
+-----
 let a = [[]];
 let b = [[], []];
 let c = [[], [], []];

crates/rome_formatter/tests/specs/js/module/array/binding_pattern.js.snap

@@ -1,6 +1,6 @@
 ---
 source: crates/rome_formatter/tests/spec_test.rs
-assertion_line: 43
+assertion_line: 157
 expression: binding_pattern.js
 
 ---
@@ -9,8 +9,13 @@ let [a,b]=c;
 let [d,...e]=c;
 let [aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb,...cccccccccccccccccccccccccccccc]=f;
 
----
-# Output
+=============================
+# Outputs
+## Output 1
+-----
+Indent style: Tab
+Line width: 80
+-----
 let [a, b] = c;
 let [d, ...e] = c;
 let [

crates/rome_formatter/tests/specs/js/module/array/empty_lines.js.snap

@@ -1,6 +1,6 @@
 ---
 source: crates/rome_formatter/tests/spec_test.rs
-assertion_line: 43
+assertion_line: 157
 expression: empty_lines.js
 
 ---
@@ -18,8 +18,13 @@ let a = [
 
   ];
 
----
-# Output
+=============================
+# Outputs
+## Output 1
+-----
+Indent style: Tab
+Line width: 80
+-----
 let a = [
 	1,
 	2,