Fix line numbers in checkstyle output (#3694)

src/emitter/checkstyle.rs

@@ -29,7 +29,7 @@ impl Emitter for CheckstyleEmitter {
             formatted_text,
         }: FormattedFile<'_>,
     ) -> Result<EmitterResult, io::Error> {
-        const CONTEXT_SIZE: usize = 3;
+        const CONTEXT_SIZE: usize = 0;
         let filename = ensure_real_path(filename);
         let diff = make_diff(original_text, formatted_text, CONTEXT_SIZE);
         output_checkstyle_file(output, filename, diff)?;
@@ -47,13 +47,18 @@ where
 {
     write!(writer, r#"<file name="{}">"#, filename.display())?;
     for mismatch in diff {
+        let begin_line = mismatch.line_number;
+        let mut current_line;
+        let mut line_counter = 0;
         for line in mismatch.lines {
             // Do nothing with `DiffLine::Context` and `DiffLine::Resulting`.
             if let DiffLine::Expected(message) = line {
+                current_line = begin_line + line_counter;
+                line_counter += 1;
                 write!(
                     writer,
                     r#"<error line="{}" severity="warning" message="Should be `{}`" />"#,
-                    mismatch.line_number,
+                    current_line,
                     XmlEscaped(&message)
                 )?;
             }
@@ -62,3 +67,82 @@ where
     write!(writer, "</file>")?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::path::PathBuf;
+
+    #[test]
+    fn emits_empty_record_on_file_with_no_mismatches() {
+        let file_name = "src/well_formatted.rs";
+        let mut writer = Vec::new();
+        let _ = output_checkstyle_file(&mut writer, &PathBuf::from(file_name), vec![]);
+        assert_eq!(
+            &writer[..],
+            format!(r#"<file name="{}"></file>"#, file_name).as_bytes()
+        );
+    }
+
+    // https://github.com/rust-lang/rustfmt/issues/1636
+    #[test]
+    fn emits_single_xml_tree_containing_all_files() {
+        let bin_file = "src/bin.rs";
+        let bin_original = vec!["fn main() {", "println!(\"Hello, world!\");", "}"];
+        let bin_formatted = vec!["fn main() {", "    println!(\"Hello, world!\");", "}"];
+        let lib_file = "src/lib.rs";
+        let lib_original = vec!["fn greet() {", "println!(\"Greetings!\");", "}"];
+        let lib_formatted = vec!["fn greet() {", "    println!(\"Greetings!\");", "}"];
+        let mut writer = Vec::new();
+        let mut emitter = CheckstyleEmitter::default();
+        let _ = emitter.emit_header(&mut writer);
+        let _ = emitter
+            .emit_formatted_file(
+                &mut writer,
+                FormattedFile {
+                    filename: &FileName::Real(PathBuf::from(bin_file)),
+                    original_text: &bin_original.join("\n"),
+                    formatted_text: &bin_formatted.join("\n"),
+                },
+            )
+            .unwrap();
+        let _ = emitter
+            .emit_formatted_file(
+                &mut writer,
+                FormattedFile {
+                    filename: &FileName::Real(PathBuf::from(lib_file)),
+                    original_text: &lib_original.join("\n"),
+                    formatted_text: &lib_formatted.join("\n"),
+                },
+            )
+            .unwrap();
+        let _ = emitter.emit_footer(&mut writer);
+        let exp_bin_xml = vec![
+            format!(r#"<file name="{}">"#, bin_file),
+            format!(
+                r#"<error line="2" severity="warning" message="Should be `{}`" />"#,
+                XmlEscaped(&r#"    println!("Hello, world!");"#),
+            ),
+            String::from("</file>"),
+        ];
+        let exp_lib_xml = vec![
+            format!(r#"<file name="{}">"#, lib_file),
+            format!(
+                r#"<error line="2" severity="warning" message="Should be `{}`" />"#,
+                XmlEscaped(&r#"    println!("Greetings!");"#),
+            ),
+            String::from("</file>"),
+        ];
+        assert_eq!(
+            String::from_utf8(writer).unwrap(),
+            vec![
+                r#"<?xml version="1.0" encoding="utf-8"?>"#,
+                "\n",
+                r#"<checkstyle version="4.3">"#,
+                &format!("{}{}", exp_bin_xml.join(""), exp_lib_xml.join("")),
+                "</checkstyle>\n",
+            ]
+            .join(""),
+        );
+    }
+}

tests/writemode/target/checkstyle.xml

@@ -1,2 +1,2 @@
 <?xml version="1.0" encoding="utf-8"?>
-<checkstyle version="4.3"><file name="tests/writemode/source/fn-single-line.rs"><error line="2" severity="warning" message="Should be `fn foo_expr() { 1 }`" /><error line="2" severity="warning" message="Should be `fn foo_stmt() { foo(); }`" /><error line="2" severity="warning" message="Should be `fn foo_decl_local() { let z = 5; }`" /><error line="2" severity="warning" message="Should be `fn foo_decl_item(x: &amp;mut i32) { x = 3; }`" /><error line="2" severity="warning" message="Should be `fn empty() {}`" /><error line="2" severity="warning" message="Should be `fn foo_return() -&gt; String { &quot;yay&quot; }`" /><error line="2" severity="warning" message="Should be `fn foo_where() -&gt; T`" /><error line="2" severity="warning" message="Should be `where`" /><error line="2" severity="warning" message="Should be `    T: Sync,`" /><error line="2" severity="warning" message="Should be `{`" /><error line="52" severity="warning" message="Should be `fn lots_of_space() { 1 }`" /><error line="59" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" /><error line="59" severity="warning" message="Should be `trait CoolerTypes {`" /><error line="59" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" /><error line="59" severity="warning" message="Should be `fn Foo&lt;T&gt;()`" /><error line="59" severity="warning" message="Should be `where`" /><error line="59" severity="warning" message="Should be `    T: Bar,`" /><error line="59" severity="warning" message="Should be `{`" /></file></checkstyle>
+<checkstyle version="4.3"><file name="tests/writemode/source/fn-single-line.rs"><error line="5" severity="warning" message="Should be `fn foo_expr() { 1 }`" /><error line="7" severity="warning" message="Should be `fn foo_stmt() { foo(); }`" /><error line="9" severity="warning" message="Should be `fn foo_decl_local() { let z = 5; }`" /><error line="11" severity="warning" message="Should be `fn foo_decl_item(x: &amp;mut i32) { x = 3; }`" /><error line="13" severity="warning" message="Should be `fn empty() {}`" /><error line="15" severity="warning" message="Should be `fn foo_return() -&gt; String { &quot;yay&quot; }`" /><error line="17" severity="warning" message="Should be `fn foo_where() -&gt; T`" /><error line="18" severity="warning" message="Should be `where`" /><error line="19" severity="warning" message="Should be `    T: Sync,`" /><error line="20" severity="warning" message="Should be `{`" /><error line="55" severity="warning" message="Should be `fn lots_of_space() { 1 }`" /><error line="60" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" /><error line="63" severity="warning" message="Should be `trait CoolerTypes {`" /><error line="64" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" /><error line="67" severity="warning" message="Should be `fn Foo&lt;T&gt;()`" /><error line="68" severity="warning" message="Should be `where`" /><error line="69" severity="warning" message="Should be `    T: Bar,`" /><error line="70" severity="warning" message="Should be `{`" /></file></checkstyle>