refactor(fmt): Track WriteStyle with the BufferWriter

src/fmt/writer/buffer/plain.rs

@@ -19,15 +19,16 @@ impl BufferWriter {
         }
     }
 
-    pub(in crate::fmt::writer) fn pipe(
-        _write_style: WriteStyle,
-        pipe: Box<Mutex<dyn io::Write + Send + 'static>>,
-    ) -> Self {
+    pub(in crate::fmt::writer) fn pipe(pipe: Box<Mutex<dyn io::Write + Send + 'static>>) -> Self {
         BufferWriter {
             target: WritableTarget::Pipe(pipe),
         }
     }
 
+    pub(in crate::fmt::writer) fn write_style(&self) -> WriteStyle {
+        WriteStyle::Never
+    }
+
     pub(in crate::fmt::writer) fn buffer(&self) -> Buffer {
         Buffer(Vec::new())
     }

src/fmt/writer/buffer/termcolor.rs

@@ -8,6 +8,7 @@ use crate::fmt::{WritableTarget, WriteStyle};
 pub(in crate::fmt::writer) struct BufferWriter {
     inner: termcolor::BufferWriter,
     uncolored_target: Option<WritableTarget>,
+    write_style: WriteStyle,
 }
 
 impl BufferWriter {
@@ -19,6 +20,7 @@ impl BufferWriter {
             } else {
                 None
             },
+            write_style,
         }
     }
 
@@ -30,20 +32,24 @@ impl BufferWriter {
             } else {
                 None
             },
+            write_style,
         }
     }
 
-    pub(in crate::fmt::writer) fn pipe(
-        write_style: WriteStyle,
-        pipe: Box<Mutex<dyn io::Write + Send + 'static>>,
-    ) -> Self {
+    pub(in crate::fmt::writer) fn pipe(pipe: Box<Mutex<dyn io::Write + Send + 'static>>) -> Self {
+        let write_style = WriteStyle::Never;
         BufferWriter {
             // The inner Buffer is never printed from, but it is still needed to handle coloring and other formatting
             inner: termcolor::BufferWriter::stderr(write_style.into_color_choice()),
             uncolored_target: Some(WritableTarget::Pipe(pipe)),
+            write_style,
         }
     }
 
+    pub(in crate::fmt::writer) fn write_style(&self) -> WriteStyle {
+        self.write_style
+    }
+
     pub(in crate::fmt::writer) fn buffer(&self) -> Buffer {
         Buffer {
             inner: self.inner.buffer(),

src/fmt/writer/mod.rs

@@ -98,12 +98,11 @@ impl WriteStyle {
 /// A terminal target with color awareness.
 pub(crate) struct Writer {
     inner: BufferWriter,
-    write_style: WriteStyle,
 }
 
 impl Writer {
     pub fn write_style(&self) -> WriteStyle {
-        self.write_style
+        self.inner.write_style()
     }
 
     pub(super) fn buffer(&self) -> Buffer {
@@ -190,17 +189,19 @@ impl Builder {
             }
             color_choice => color_choice,
         };
+        let color_choice = if self.is_test {
+            WriteStyle::Never
+        } else {
+            color_choice
+        };
 
         let writer = match mem::take(&mut self.target) {
             Target::Stderr => BufferWriter::stderr(self.is_test, color_choice),
             Target::Stdout => BufferWriter::stdout(self.is_test, color_choice),
-            Target::Pipe(pipe) => BufferWriter::pipe(color_choice, Box::new(Mutex::new(pipe))),
+            Target::Pipe(pipe) => BufferWriter::pipe(Box::new(Mutex::new(pipe))),
         };
 
-        Writer {
-            inner: writer,
-            write_style: self.write_style,
-        }
+        Writer { inner: writer }
     }
 }