test: update error message formatting

Cargo.toml

@@ -123,3 +123,4 @@ smallvec = "1"
 tikv-jemallocator = "0.5.4"
 unicode-width = "0.1.11"
 vergen = "8.3"
+yansi = "1.0"

tools/tester/Cargo.toml

@@ -27,6 +27,7 @@ tempfile.workspace = true
 tester.workspace = true
 unified-diff.workspace = true
 walkdir.workspace = true
+yansi = { workspace = true, features = ["detect-env", "detect-tty"] }
 
 [features]
 nightly = []

tools/tester/src/context.rs

@@ -367,19 +367,24 @@ impl TestCx<'_> {
         }
 
         if !unexpected.is_empty() || !not_found.is_empty() {
-            self.error(&format!(
-                "{} unexpected errors found, {} expected errors not found",
-                unexpected.len(),
-                not_found.len()
-            ));
-            println!("status: {}\ncommand: {}", output.status, output.cmdline);
+            use yansi::Paint;
+
+            println!("status: {}\ncommand: {}\n", output.status, output.cmdline);
             if !unexpected.is_empty() {
-                println!("unexpected errors (from JSON output): {unexpected:#?}\n");
+                println!("{}", "--- unexpected errors (from JSON output) ---".green());
+                for error in &unexpected {
+                    println!("{}", error.render_for_expected());
+                }
+                println!("{}", "---".green());
             }
             if !not_found.is_empty() {
-                println!("not found errors (from test file): {not_found:#?}\n");
+                println!("{}", "--- not found errors (from test file) ---".red());
+                for error in &not_found {
+                    println!("{}", error.render_for_expected());
+                }
+                println!("{}", "---\n".red());
             }
-            panic!();
+            panic!("errors differ from expected");
         }
     }
 

tools/tester/src/errors.rs

@@ -130,6 +130,18 @@ impl Error {
     }
 }
 
+impl Error {
+    pub fn render_for_expected(&self) -> String {
+        use yansi::Paint;
+        format!(
+            "{: <10}line {: >3}: {}",
+            self.kind.map(|kind| kind.to_string()).unwrap_or_default().to_uppercase(),
+            self.line_num,
+            self.msg.cyan(),
+        )
+    }
+}
+
 #[derive(PartialEq, Debug)]
 enum WhichLine {
     ThisLine,

tools/tester/src/lib.rs

@@ -38,6 +38,8 @@ mod utils;
 use utils::TestResult;
 
 pub fn run_tests(cmd: &'static Path) -> i32 {
+    utils::enable_paint();
+
     let args = std::env::args().collect::<Vec<_>>();
     let mut opts = match test::test::parse_opts(&args) {
         Some(Ok(o)) => o,

tools/tester/src/utils.rs

@@ -24,3 +24,9 @@ pub(crate) fn path_contains(haystack: &Path, needle: &str) -> bool {
     let s = s.replace('\\', "/");
     s.contains(needle)
 }
+
+/// Sets the default [`yansi`] color output condition.
+pub(crate) fn enable_paint() {
+    let enable = yansi::Condition::os_support() && yansi::Condition::tty_and_color_live();
+    yansi::whenever(yansi::Condition::cached(enable));
+}