Add test to ensure that no DOS backline (\r\n) doesn't create extra backline in source rendering

src/librustdoc/html/highlight.rs

@@ -21,8 +21,6 @@ pub fn render_with_highlighting(
     playground_button: Option<&str>,
     tooltip: Option<(&str, &str)>,
 ) -> String {
-    // This replace allows to fix how the code source with DOS backline characters is displayed.
-    let src = src.replace("\r\n", "\n");
     debug!("highlighting: ================\n{}\n==============", src);
     let mut out = String::with_capacity(src.len());
     if let Some((tooltip, class)) = tooltip {
@@ -48,7 +46,9 @@ fn write_header(out: &mut String, class: Option<&str>) {
 }
 
 fn write_code(out: &mut String, src: &str) {
-    Classifier::new(src).highlight(&mut |highlight| {
+    // This replace allows to fix how the code source with DOS backline characters is displayed.
+    let src = src.replace("\r\n", "\n");
+    Classifier::new(&src).highlight(&mut |highlight| {
         match highlight {
             Highlight::Token { text, class } => string(out, Escape(text), class),
             Highlight::EnterSpan { class } => enter_span(out, class),

src/librustdoc/html/highlight/fixtures/dos_line.html

@@ -0,0 +1,3 @@
+<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">foo</span>() {
+<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;foo&quot;</span>);
+}

src/librustdoc/html/highlight/tests.rs

@@ -1,17 +1,6 @@
 use super::write_code;
 use expect_test::expect_file;
 
-#[test]
-fn test_html_highlighting() {
-    let src = include_str!("fixtures/sample.rs");
-    let html = {
-        let mut out = String::new();
-        write_code(&mut out, src);
-        format!("{}<pre><code>{}</code></pre>\n", STYLE, out)
-    };
-    expect_file!["fixtures/sample.html"].assert_eq(&html);
-}
-
 const STYLE: &str = r#"
 <style>
 .kw { color: #8959A8; }
@@ -23,3 +12,24 @@ const STYLE: &str = r#"
 .question-mark { color: #ff9011; }
 </style>
 "#;
+
+#[test]
+fn test_html_highlighting() {
+    let src = include_str!("fixtures/sample.rs");
+    let html = {
+        let mut out = String::new();
+        write_code(&mut out, src);
+        format!("{}<pre><code>{}</code></pre>\n", STYLE, out)
+    };
+    expect_file!["fixtures/sample.html"].assert_eq(&html);
+}
+
+#[test]
+fn test_dos_backline() {
+    let src = "pub fn foo() {\r\n\
+    println!(\"foo\");\r\n\
+}\r\n";
+    let mut html = String::new();
+    write_code(&mut html, src);
+    expect_file!["fixtures/dos_line.html"].assert_eq(&html);
+}