feat: add json(c) support to deno fmt (#9292)

This commit adds support for formatting JSON and JSONC 
in "deno fmt".

New values "json" and "jsonc" are added to "--ext" flag for 
standard input processing.

13 files changed, 166 insertions, 44 deletions

diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index e8e90190a..f05865faf 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -48,6 +48,7 @@ clap = "2.33.3"
 dissimilar = "1.0.2"
 dprint-plugin-typescript = "0.40.1"
 dprint-plugin-markdown = "0.5.1"
+dprint-plugin-json = "0.8.0"
 encoding_rs = "0.8.28"
 env_logger = "0.8.2"
 filetime = "0.2.14"
diff --git a/cli/flags.rs b/cli/flags.rs
index 80ad6e240..c58e3e3d4 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -797,7 +797,7 @@ fn fmt_subcommand<'a, 'b>() -> App<'a, 'b> {
   SubCommand::with_name("fmt")
     .about("Format source files")
     .long_about(
-      "Auto-format JavaScript, TypeScript and Markdown files.
+      "Auto-format JavaScript, TypeScript, Markdown, and JSON files.
   deno fmt
   deno fmt myfile1.ts myfile2.ts
   deno fmt --check
@@ -823,7 +823,7 @@ Ignore formatting a file by adding an ignore comment at the top of the file:
         .help("Set standard input (stdin) content type")
         .takes_value(true)
         .default_value("ts")
-        .possible_values(&["ts", "tsx", "js", "jsx", "md"]),
+        .possible_values(&["ts", "tsx", "js", "jsx", "md", "json", "jsonc"]),
     )
     .arg(
       Arg::with_name("ignore")
diff --git a/cli/fs_util.rs b/cli/fs_util.rs
index a6cd06e78..04cdfff75 100644
--- a/cli/fs_util.rs
+++ b/cli/fs_util.rs
@@ -97,10 +97,14 @@ pub fn is_supported_ext(path: &Path) -> bool {
   }
 }
 
-/// This function is similar to is_supported_ext but also allows .md extension.
-pub fn is_supported_ext_md(path: &Path) -> bool {
+/// This function is similar to is_supported_ext but adds additional extensions
+/// supported by `deno fmt`.
+pub fn is_supported_ext_fmt(path: &Path) -> bool {
   if let Some(ext) = get_extension(path) {
-    matches!(ext.as_str(), "ts" | "tsx" | "js" | "jsx" | "mjs" | "md")
+    matches!(
+      ext.as_str(),
+      "ts" | "tsx" | "js" | "jsx" | "mjs" | "md" | "json" | "jsonc"
+    )
   } else {
     false
   }
@@ -221,21 +225,25 @@ mod tests {
   }
 
   #[test]
-  fn test_is_supported_ext_md() {
-    assert!(!is_supported_ext_md(Path::new("tests/subdir/redirects")));
-    assert!(is_supported_ext_md(Path::new("README.md")));
-    assert!(is_supported_ext_md(Path::new("readme.MD")));
-    assert!(is_supported_ext_md(Path::new("lib/typescript.d.ts")));
-    assert!(is_supported_ext_md(Path::new("cli/tests/001_hello.js")));
-    assert!(is_supported_ext_md(Path::new("cli/tests/002_hello.ts")));
-    assert!(is_supported_ext_md(Path::new("foo.jsx")));
-    assert!(is_supported_ext_md(Path::new("foo.tsx")));
-    assert!(is_supported_ext_md(Path::new("foo.TS")));
-    assert!(is_supported_ext_md(Path::new("foo.TSX")));
-    assert!(is_supported_ext_md(Path::new("foo.JS")));
-    assert!(is_supported_ext_md(Path::new("foo.JSX")));
-    assert!(is_supported_ext_md(Path::new("foo.mjs")));
-    assert!(!is_supported_ext_md(Path::new("foo.mjsx")));
+  fn test_is_supported_ext_fmt() {
+    assert!(!is_supported_ext_fmt(Path::new("tests/subdir/redirects")));
+    assert!(is_supported_ext_fmt(Path::new("README.md")));
+    assert!(is_supported_ext_fmt(Path::new("readme.MD")));
+    assert!(is_supported_ext_fmt(Path::new("lib/typescript.d.ts")));
+    assert!(is_supported_ext_fmt(Path::new("cli/tests/001_hello.js")));
+    assert!(is_supported_ext_fmt(Path::new("cli/tests/002_hello.ts")));
+    assert!(is_supported_ext_fmt(Path::new("foo.jsx")));
+    assert!(is_supported_ext_fmt(Path::new("foo.tsx")));
+    assert!(is_supported_ext_fmt(Path::new("foo.TS")));
+    assert!(is_supported_ext_fmt(Path::new("foo.TSX")));
+    assert!(is_supported_ext_fmt(Path::new("foo.JS")));
+    assert!(is_supported_ext_fmt(Path::new("foo.JSX")));
+    assert!(is_supported_ext_fmt(Path::new("foo.mjs")));
+    assert!(!is_supported_ext_fmt(Path::new("foo.mjsx")));
+    assert!(is_supported_ext_fmt(Path::new("foo.jsonc")));
+    assert!(is_supported_ext_fmt(Path::new("foo.JSONC")));
+    assert!(is_supported_ext_fmt(Path::new("foo.json")));
+    assert!(is_supported_ext_fmt(Path::new("foo.JsON")));
   }
 
   #[test]
diff --git a/cli/tests/badly_formatted.json b/cli/tests/badly_formatted.json
new file mode 100644
index 000000000..f2bacf73d
--- /dev/null
+++ b/cli/tests/badly_formatted.json
@@ -0,0 +1,12 @@
+{
+
+
+  "key1":     "value1",
+          "key2": true,
+          "key3": ["value2",     "value3", false],
+          "keys": {
+            "more": "values"
+          }
+
+
+}
\ No newline at end of file
diff --git a/cli/tests/badly_formatted.md b/cli/tests/badly_formatted.md
index adffe3e46..26afe483b 100644
--- a/cli/tests/badly_formatted.md
+++ b/cli/tests/badly_formatted.md
@@ -25,4 +25,22 @@ hello(        "alice");
 function foo(): number {
   return       2;
 }
+```
+
+```jsonc
+
+{
+  // Comment in JSON
+  "key":          "value",
+                "key2":      
+                "value2",
+}
+
+```
+
+```json
+{
+  "numbers":
+  ["1",      "2"]
+}
 ```
\ No newline at end of file
diff --git a/cli/tests/badly_formatted_fixed.json b/cli/tests/badly_formatted_fixed.json
new file mode 100644
index 000000000..0d697a2c6
--- /dev/null
+++ b/cli/tests/badly_formatted_fixed.json
@@ -0,0 +1,8 @@
+{
+  "key1": "value1",
+  "key2": true,
+  "key3": ["value2", "value3", false],
+  "keys": {
+    "more": "values"
+  }
+}
diff --git a/cli/tests/badly_formatted_fixed.md b/cli/tests/badly_formatted_fixed.md
index 359a8aead..8ba74cac3 100644
--- a/cli/tests/badly_formatted_fixed.md
+++ b/cli/tests/badly_formatted_fixed.md
@@ -21,3 +21,17 @@ function foo(): number {
   return 2;
 }
 ```
+
+```jsonc
+{
+  // Comment in JSON
+  "key": "value",
+  "key2": "value2"
+}
+```
+
+```json
+{
+  "numbers": ["1", "2"]
+}
+```
diff --git a/cli/tests/fmt/expected_fmt_check_formatted_files.out b/cli/tests/fmt/expected_fmt_check_formatted_files.out
index 7c1e471b9..5a4833dd4 100644
--- a/cli/tests/fmt/expected_fmt_check_formatted_files.out
+++ b/cli/tests/fmt/expected_fmt_check_formatted_files.out
@@ -1 +1 @@
-Checked 3 files
+Checked 4 files
diff --git a/cli/tests/fmt/expected_fmt_check_ignore.out b/cli/tests/fmt/expected_fmt_check_ignore.out
index 158c556c2..7c1e471b9 100644
--- a/cli/tests/fmt/expected_fmt_check_ignore.out
+++ b/cli/tests/fmt/expected_fmt_check_ignore.out
@@ -1 +1 @@
-Checked 2 files
+Checked 3 files
diff --git a/cli/tests/fmt/expected_fmt_check_tests_dir.out b/cli/tests/fmt/expected_fmt_check_tests_dir.out
index e2dc2b4ae..fe84cd485 100644
--- a/cli/tests/fmt/expected_fmt_check_tests_dir.out
+++ b/cli/tests/fmt/expected_fmt_check_tests_dir.out
@@ -1,2 +1,2 @@
 [WILDCARD]
-error: Found 6 not formatted files in [WILDCARD] files
+error: Found 7 not formatted files in [WILDCARD] files
diff --git a/cli/tests/fmt/formatted4.jsonc b/cli/tests/fmt/formatted4.jsonc
new file mode 100644
index 000000000..f0f72a6ed
--- /dev/null
+++ b/cli/tests/fmt/formatted4.jsonc
@@ -0,0 +1,4 @@
+{
+  // Comment
+  "key": "value"
+}
diff --git a/cli/tests/integration_tests.rs b/cli/tests/integration_tests.rs
index 988372b17..b55111154 100644
--- a/cli/tests/integration_tests.rs
+++ b/cli/tests/integration_tests.rs
@@ -496,30 +496,43 @@ mod integration {
   fn fmt_test() {
     let t = TempDir::new().expect("tempdir fail");
     let fixed_js = util::root_path().join("cli/tests/badly_formatted_fixed.js");
-    let fixed_md = util::root_path().join("cli/tests/badly_formatted_fixed.md");
     let badly_formatted_original_js =
       util::root_path().join("cli/tests/badly_formatted.mjs");
-    let badly_formatted_original_md =
-      util::root_path().join("cli/tests/badly_formatted.md");
     let badly_formatted_js = t.path().join("badly_formatted.js");
-    let badly_formatted_md = t.path().join("badly_formatted.md");
     let badly_formatted_js_str = badly_formatted_js.to_str().unwrap();
-    let badly_formatted_md_str = badly_formatted_md.to_str().unwrap();
     std::fs::copy(&badly_formatted_original_js, &badly_formatted_js)
       .expect("Failed to copy file");
+
+    let fixed_md = util::root_path().join("cli/tests/badly_formatted_fixed.md");
+    let badly_formatted_original_md =
+      util::root_path().join("cli/tests/badly_formatted.md");
+    let badly_formatted_md = t.path().join("badly_formatted.md");
+    let badly_formatted_md_str = badly_formatted_md.to_str().unwrap();
     std::fs::copy(&badly_formatted_original_md, &badly_formatted_md)
       .expect("Failed to copy file");
+
+    let fixed_json =
+      util::root_path().join("cli/tests/badly_formatted_fixed.json");
+    let badly_formatted_original_json =
+      util::root_path().join("cli/tests/badly_formatted.json");
+    let badly_formatted_json = t.path().join("badly_formatted.json");
+    let badly_formatted_json_str = badly_formatted_json.to_str().unwrap();
+    std::fs::copy(&badly_formatted_original_json, &badly_formatted_json)
+      .expect("Failed to copy file");
     // First, check formatting by ignoring the badly formatted file.
     let status = util::deno_cmd()
       .current_dir(util::root_path())
       .arg("fmt")
       .arg(format!(
-        "--ignore={},{}",
-        badly_formatted_js_str, badly_formatted_md_str
+        "--ignore={},{},{}",
+        badly_formatted_js_str,
+        badly_formatted_md_str,
+        badly_formatted_json_str
       ))
       .arg("--check")
       .arg(badly_formatted_js_str)
       .arg(badly_formatted_md_str)
+      .arg(badly_formatted_json_str)
       .spawn()
       .expect("Failed to spawn script")
       .wait()
@@ -532,6 +545,7 @@ mod integration {
       .arg("--check")
       .arg(badly_formatted_js_str)
       .arg(badly_formatted_md_str)
+      .arg(badly_formatted_json_str)
       .spawn()
       .expect("Failed to spawn script")
       .wait()
@@ -543,6 +557,7 @@ mod integration {
       .arg("fmt")
       .arg(badly_formatted_js_str)
       .arg(badly_formatted_md_str)
+      .arg(badly_formatted_json_str)
       .spawn()
       .expect("Failed to spawn script")
       .wait()
@@ -550,10 +565,13 @@ mod integration {
     assert!(status.success());
     let expected_js = std::fs::read_to_string(fixed_js).unwrap();
     let expected_md = std::fs::read_to_string(fixed_md).unwrap();
+    let expected_json = std::fs::read_to_string(fixed_json).unwrap();
     let actual_js = std::fs::read_to_string(badly_formatted_js).unwrap();
     let actual_md = std::fs::read_to_string(badly_formatted_md).unwrap();
+    let actual_json = std::fs::read_to_string(badly_formatted_json).unwrap();
     assert_eq!(expected_js, actual_js);
     assert_eq!(expected_md, actual_md);
+    assert_eq!(expected_json, actual_json);
   }
 
   mod file_watcher {
@@ -2838,7 +2856,7 @@ console.log("finish");
   });
 
   itest!(fmt_check_tests_dir {
-    args: "fmt --check ./",
+    args: "fmt --check ./ --ignore=.test_coverage",
     output: "fmt/expected_fmt_check_tests_dir.out",
     exit_code: 1,
   });
@@ -2850,7 +2868,7 @@ console.log("finish");
   });
 
   itest!(fmt_check_formatted_files {
-    args: "fmt --check fmt/formatted1.js fmt/formatted2.ts fmt/formatted3.md",
+    args: "fmt --check fmt/formatted1.js fmt/formatted2.ts fmt/formatted3.md fmt/formatted4.jsonc",
     output: "fmt/expected_fmt_check_formatted_files.out",
     exit_code: 0,
   });
@@ -2875,6 +2893,12 @@ console.log("finish");
     ),
   });
 
+  itest!(fmt_stdin_json {
+    args: "fmt --ext=json -",
+    input: Some("{    \"key\":   \"value\"}"),
+    output_str: Some("{ \"key\": \"value\" }\n"),
+  });
+
   itest!(fmt_stdin_check_formatted {
     args: "fmt --check -",
     input: Some("const a = 1;\n"),
diff --git a/cli/tools/fmt.rs b/cli/tools/fmt.rs
index 61875d172..d4002984a 100644
--- a/cli/tools/fmt.rs
+++ b/cli/tools/fmt.rs
@@ -10,7 +10,7 @@
 use crate::colors;
 use crate::diff::diff;
 use crate::file_watcher;
-use crate::fs_util::{collect_files, get_extension, is_supported_ext_md};
+use crate::fs_util::{collect_files, get_extension, is_supported_ext_fmt};
 use crate::text_encoding;
 use deno_core::error::generic_error;
 use deno_core::error::AnyError;
@@ -37,7 +37,7 @@ pub async fn format(
 ) -> Result<(), AnyError> {
   let target_file_resolver = || {
     // collect the files that are to be formatted
-    collect_files(&args, &ignore, is_supported_ext_md)
+    collect_files(&args, &ignore, is_supported_ext_fmt)
   };
   let operation = |paths: Vec<PathBuf>| {
     let config = get_typescript_config();
@@ -75,7 +75,14 @@ fn format_markdown(
       let tag = tag.to_lowercase();
       if matches!(
         tag.as_str(),
-        "ts" | "tsx" | "js" | "jsx" | "javascript" | "typescript"
+        "ts"
+          | "tsx"
+          | "js"
+          | "jsx"
+          | "javascript"
+          | "typescript"
+          | "json"
+          | "jsonc"
       ) {
         // It's important to tell dprint proper file extension, otherwise
         // it might parse the file twice.
@@ -84,16 +91,22 @@ fn format_markdown(
           "typescript" => "ts",
           rest => rest,
         };
-        let fake_filename =
-          PathBuf::from(format!("deno_fmt_stdin.{}", extension));
 
-        let mut codeblock_config = ts_config.clone();
-        codeblock_config.line_width = line_width;
-        dprint_plugin_typescript::format_text(
-          &fake_filename,
-          &text,
-          &codeblock_config,
-        )
+        if matches!(extension, "json" | "jsonc") {
+          let mut json_config = get_json_config();
+          json_config.line_width = line_width;
+          dprint_plugin_json::format_text(&text, &json_config)
+        } else {
+          let fake_filename =
+            PathBuf::from(format!("deno_fmt_stdin.{}", extension));
+          let mut codeblock_config = ts_config.clone();
+          codeblock_config.line_width = line_width;
+          dprint_plugin_typescript::format_text(
+            &fake_filename,
+            &text,
+            &codeblock_config,
+          )
+        }
       } else {
         Ok(text.to_string())
       }
@@ -101,6 +114,14 @@ fn format_markdown(
   )
 }
 
+/// Formats JSON and JSONC using the rules provided by .deno()
+/// of configuration builder of https://github.com/dprint/dprint-plugin-json.
+/// See https://git.io/Jt4ht for configuration.
+fn format_json(file_text: &str) -> Result<String, String> {
+  let json_config = get_json_config();
+  dprint_plugin_json::format_text(&file_text, &json_config)
+}
+
 async fn check_source_files(
   config: dprint_plugin_typescript::configuration::Configuration,
   paths: Vec<PathBuf>,
@@ -120,6 +141,8 @@ async fn check_source_files(
       let ext = get_extension(&file_path).unwrap_or_else(String::new);
       let r = if ext == "md" {
         format_markdown(&file_text, config.clone())
+      } else if matches!(ext.as_str(), "json" | "jsonc") {
+        format_json(&file_text)
       } else {
         dprint_plugin_typescript::format_text(&file_path, &file_text, &config)
       };
@@ -179,6 +202,8 @@ async fn format_source_files(
       let ext = get_extension(&file_path).unwrap_or_else(String::new);
       let r = if ext == "md" {
         format_markdown(&file_contents.text, config.clone())
+      } else if matches!(ext.as_str(), "json" | "jsonc") {
+        format_json(&file_contents.text)
       } else {
         dprint_plugin_typescript::format_text(
           &file_path,
@@ -240,6 +265,8 @@ pub fn format_stdin(check: bool, ext: String) -> Result<(), AnyError> {
   let config = get_typescript_config();
   let r = if ext.as_str() == "md" {
     format_markdown(&source, config)
+  } else if matches!(ext.as_str(), "json" | "jsonc") {
+    format_json(&source)
   } else {
     // dprint will fallback to jsx parsing if parsing this as a .ts file doesn't work
     dprint_plugin_typescript::format_text(
@@ -291,6 +318,12 @@ fn get_markdown_config() -> dprint_plugin_markdown::configuration::Configuration
     .build()
 }
 
+fn get_json_config() -> dprint_plugin_json::configuration::Configuration {
+  dprint_plugin_json::configuration::ConfigurationBuilder::new()
+    .deno()
+    .build()
+}
+
 struct FileContents {
   text: String,
   had_bom: bool,