2 files changed, 168 insertions, 0 deletions
diff --git a/third_party/rust/codespan-reporting/tests/support/color_buffer.rs b/third_party/rust/codespan-reporting/tests/support/color_buffer.rs
new file mode 100644
index 0000000000..b51360ce63
--- /dev/null
+++ b/third_party/rust/codespan-reporting/tests/support/color_buffer.rs
@@ -0,0 +1,137 @@
+use std::io;
+use std::io::prelude::*;
+use termcolor::{ColorSpec, WriteColor};
+
+// Color tester from:
+// https://github.com/wycats/language-reporting/blob/b021c87e0d4916b5f32756151bf215c220eee52d/crates/render-tree/src/stylesheet/accumulator.rs
+
+/// A facility for creating visually inspectable representations of colored output
+/// so they can be easily tested.
+///
+/// A new color is represented as `{style}` and a reset is represented by `{/}`.
+///
+/// Attributes are printed in this order:
+///
+/// - Foreground color as `fg:Color`
+/// - Background color as `bg:Color`
+/// - Bold as `bold`
+/// - Underline as `underline`
+/// - Intense as `bright`
+///
+/// For example, the style "intense, bold red foreground" would be printed as:
+///
+/// ```text
+/// {fg:Red bold intense}
+/// ```
+///
+/// Since this implementation attempts to make it possible to faithfully
+/// understand what real WriteColor implementations would do, it tries
+/// to approximate the contract in the WriteColor trait: "Subsequent
+/// writes to this write will use these settings until either reset is
+/// called or new color settings are set.")
+///
+/// - If set_color is called with a style, `{...}` is emitted containing the
+///   color attributes.
+/// - If set_color is called with no style, `{/}` is emitted
+/// - If reset is called, `{/}` is emitted.
+pub struct ColorBuffer {
+    buf: Vec<u8>,
+    color: ColorSpec,
+}
+
+impl ColorBuffer {
+    pub fn new() -> ColorBuffer {
+        ColorBuffer {
+            buf: Vec::new(),
+            color: ColorSpec::new(),
+        }
+    }
+
+    pub fn into_string(self) -> String {
+        String::from_utf8(self.buf).unwrap()
+    }
+}
+
+impl io::Write for ColorBuffer {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.buf.extend(buf);
+        Ok(buf.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+impl WriteColor for ColorBuffer {
+    fn supports_color(&self) -> bool {
+        true
+    }
+
+    fn set_color(&mut self, spec: &ColorSpec) -> io::Result<()> {
+        #![allow(unused_assignments)]
+
+        if self.color == *spec {
+            return Ok(());
+        } else {
+            self.color = spec.clone();
+        }
+
+        if spec.is_none() {
+            write!(self, "{{/}}")?;
+            return Ok(());
+        } else {
+            write!(self, "{{")?;
+        }
+
+        let mut first = true;
+
+        fn write_first(first: bool, write: &mut ColorBuffer) -> io::Result<bool> {
+            if !first {
+                write!(write, " ")?;
+            }
+
+            Ok(false)
+        };
+
+        if let Some(fg) = spec.fg() {
+            first = write_first(first, self)?;
+            write!(self, "fg:{:?}", fg)?;
+        }
+
+        if let Some(bg) = spec.bg() {
+            first = write_first(first, self)?;
+            write!(self, "bg:{:?}", bg)?;
+        }
+
+        if spec.bold() {
+            first = write_first(first, self)?;
+            write!(self, "bold")?;
+        }
+
+        if spec.underline() {
+            first = write_first(first, self)?;
+            write!(self, "underline")?;
+        }
+
+        if spec.intense() {
+            first = write_first(first, self)?;
+            write!(self, "bright")?;
+        }
+
+        write!(self, "}}")?;
+
+        Ok(())
+    }
+
+    fn reset(&mut self) -> io::Result<()> {
+        let color = self.color.clone();
+
+        if color != ColorSpec::new() {
+            write!(self, "{{/}}")?;
+            self.color = ColorSpec::new();
+        }
+
+        Ok(())
+    }
+}
diff --git a/third_party/rust/codespan-reporting/tests/support/mod.rs b/third_party/rust/codespan-reporting/tests/support/mod.rs
new file mode 100644
index 0000000000..4f7313ac36
--- /dev/null
+++ b/third_party/rust/codespan-reporting/tests/support/mod.rs
@@ -0,0 +1,31 @@
+use codespan_reporting::diagnostic::Diagnostic;
+use codespan_reporting::files::Files;
+use codespan_reporting::term::{emit, Config};
+use termcolor::{Buffer, WriteColor};
+
+mod color_buffer;
+
+use self::color_buffer::ColorBuffer;
+
+pub struct TestData<'files, F: Files<'files>> {
+    pub files: F,
+    pub diagnostics: Vec<Diagnostic<F::FileId>>,
+}
+
+impl<'files, F: Files<'files>> TestData<'files, F> {
+    fn emit<W: WriteColor>(&'files self, mut writer: W, config: &Config) -> W {
+        for diagnostic in &self.diagnostics {
+            emit(&mut writer, config, &self.files, &diagnostic).unwrap();
+        }
+        writer
+    }
+
+    pub fn emit_color(&'files self, config: &Config) -> String {
+        self.emit(ColorBuffer::new(), &config).into_string()
+    }
+
+    pub fn emit_no_color(&'files self, config: &Config) -> String {
+        let buffer = self.emit(Buffer::no_color(), &config);
+        String::from_utf8_lossy(buffer.as_slice()).into_owned()
+    }
+}