feat: Disable colored output when NO_COLOR env is present

bin/src/traits.rs

@@ -1,4 +1,5 @@
 use std::{
+    env,
     io::{self, Write},
     str,
 };
@@ -46,6 +47,7 @@ fn write_stderr<T: Write>(
     lint_result: &LintResult,
     vfs: &ReadOnlyVfs,
 ) -> io::Result<()> {
+    let no_color = env::var("NO_COLOR").is_ok();
     let file_id = lint_result.file_id;
     let src = str::from_utf8(vfs.get(file_id)).unwrap();
     let path = vfs.file_path(file_id);
@@ -70,6 +72,7 @@ fn write_stderr<T: Write>(
                 CliReport::build(report_kind, src_id, offset)
                     .with_config(
                         CliConfig::default()
+                            .with_color(!no_color)
                             .with_cross_gap(true)
                             .with_multiline_arrows(false)
                             .with_label_attach(LabelAttach::Middle)
@@ -78,11 +81,16 @@ fn write_stderr<T: Write>(
                     .with_message(report.note)
                     .with_code(report.code),
                 |cli_report, diagnostic| {
-                    cli_report.with_label(
-                        Label::new((src_id, range(diagnostic.at)))
+                    let mut label = Label::new((src_id, range(diagnostic.at)));
+                    if no_color {
+                        label =
+                            label.with_message(diagnostic.message.split('`').collect::<String>());
+                    } else {
+                        label = label
                             .with_message(colorize(&diagnostic.message))
-                            .with_color(Color::Magenta),
-                    )
+                            .with_color(Color::Magenta);
+                    }
+                    cli_report.with_label(label)
                 },
             )
             .finish()

bin/tests/_utils.rs

@@ -1,8 +1,15 @@
-use std::{io::Write, process::Command};
+use std::{collections::HashMap, io::Write, process::Command};
 
 use tempfile::NamedTempFile;
 
-pub fn test_cli(expression: &str, args: &[&str]) -> anyhow::Result<String> {
+pub fn test_cli(
+    expression: &str,
+    args: &[&str],
+    envs: HashMap<&str, &str>,
+    output_processing: OutputProcessing,
+) -> anyhow::Result<String>
+where
+{
     let mut fixture = NamedTempFile::with_suffix(".nix")?;
     fixture.write_all(expression.as_bytes())?;
     fixture.write_all(b"\n")?; // otherwise diff says there's no newline at end of file
@@ -12,11 +19,21 @@ pub fn test_cli(expression: &str, args: &[&str]) -> anyhow::Result<String> {
         .arg("--")
         .args(args)
         .arg(fixture.path())
+        .envs(envs)
         .output()?;
 
-    let stdout = strip_ansi_escapes::strip(output.stdout)?;
+    let stdout = match output_processing {
+        OutputProcessing::Unchanged => output.stdout,
+        OutputProcessing::StripAnsi => strip_ansi_escapes::strip(output.stdout)?,
+    };
     let stdout = String::from_utf8(stdout)?;
     let stdout = stdout.replace(fixture.path().to_str().unwrap(), "<temp_file_path>");
 
     Ok(stdout)
 }
+
+#[allow(unused)]
+pub enum OutputProcessing {
+    Unchanged,
+    StripAnsi,
+}

bin/tests/no_color.rs

@@ -0,0 +1,36 @@
+mod _utils;
+
+use crate::_utils::OutputProcessing;
+use std::collections::HashMap;
+
+const EXPR: &'static str = "let in null";
+
+#[test]
+fn test_output_with_color_ansi_escape() {
+    let stdout = _utils::test_cli(
+        EXPR,
+        &["check"],
+        HashMap::new(),
+        OutputProcessing::Unchanged,
+    )
+    .unwrap();
+    let snapshot = format!("{EXPR}\n---\n{stdout}");
+    insta::with_settings!({omit_expression => true}, {
+        insta::assert_snapshot!("output_with_color_ansi_escape", snapshot);
+    });
+}
+
+#[test]
+fn test_output_without_color_ansi_escape() {
+    let stdout = _utils::test_cli(
+        EXPR,
+        &["check"],
+        HashMap::from([("NO_COLOR", "1")]),
+        OutputProcessing::Unchanged,
+    )
+    .unwrap();
+    let snapshot = format!("{EXPR}\n---\n{stdout}");
+    insta::with_settings!({omit_expression => true}, {
+        insta::assert_snapshot!("output_without_color_ansi_escape", snapshot);
+    });
+}

bin/tests/snapshots/no_color__output_with_color_ansi_escape.snap

@@ -0,0 +1,12 @@
+---
+source: bin/tests/no_color.rs
+---
+let in null
+---
+[W02] Warning: Useless let-in expression
+   ╭─[<temp_file_path>:1:1]
+   │
+ 1 │ let in null
+   · ─────┬─────  
+   ·      ╰─────── This let-in expression has no entries
+───╯

bin/tests/snapshots/no_color__output_without_color_ansi_escape.snap

@@ -0,0 +1,12 @@
+---
+source: bin/tests/no_color.rs
+---
+let in null
+---
+[W02] Warning: Useless let-in expression
+   ╭─[<temp_file_path>:1:1]
+   │
+ 1 │ let in null
+   · ─────┬─────  
+   ·      ╰─────── This let-in expression has no entries
+───╯

macros/src/test.rs

@@ -95,8 +95,11 @@ fn make_test(rule: &Ident, kind: TestKind, nix_expression: &Expr) -> proc_macro2
     quote! {
         #[test]
         fn #test_ident() {
+            use std::collections::HashMap;
+            use crate::_utils::OutputProcessing;
+
             let expression = #nix_expression;
-            let stdout = _utils::test_cli(expression, #args).unwrap();
+            let stdout = _utils::test_cli(expression, #args, HashMap::new(), OutputProcessing::StripAnsi).unwrap();
             let snapshot = format!("{expression}\n---\n{stdout}");
             insta::with_settings!({omit_expression => true}, {
                 insta::assert_snapshot!(#snap_name, snapshot);

readme.md

@@ -152,3 +152,8 @@ useless_has_attr
 
 All lints are enabled by default. Generate a minimal config
 with `statix dump > statix.toml`.
+
+### Color
+
+Reports contain ANSI color escape codes unless the
+[`NO_COLOR`](https://no-color.org/) environment variable is present.