test: Add a test for passing precolored text

examples/highlight_title.rs

@@ -0,0 +1,68 @@
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
+use anstyle::Effects;
+
+fn main() {
+    let source = r#"// Make sure "highlighted" code is colored purple
+
+//@ compile-flags: --error-format=human --color=always
+//@ error-pattern:for<'a> 
+//@ edition:2018
+
+use core::pin::Pin;
+use core::future::Future;
+use core::any::Any;
+
+fn query(_: fn(Box<(dyn Any + Send + '_)>) -> Pin<Box<(
+    dyn Future<Output = Result<Box<(dyn Any + 'static)>, String>> + Send + 'static
+)>>) {}
+
+fn wrapped_fn<'a>(_: Box<(dyn Any + Send)>) -> Pin<Box<(
+    dyn Future<Output = Result<Box<(dyn Any + 'static)>, String>> + Send + 'static
+)>> {
+    Box::pin(async { Err("nope".into()) })
+}
+
+fn main() {
+    query(wrapped_fn);
+}
+"#;
+
+    let magenta = annotate_snippets::renderer::AnsiColor::Magenta
+        .on_default()
+        .effects(Effects::BOLD);
+    let title = format!(
+        "expected fn pointer `{}for<'a>{} fn(Box<{}(dyn Any + Send + 'a){}>) -> Pin<_>`
+      found fn item `fn(Box<{}(dyn Any + Send + 'static){}>) -> Pin<_> {}{{wrapped_fn}}{}`",
+        magenta.render(),
+        magenta.render_reset(),
+        magenta.render(),
+        magenta.render_reset(),
+        magenta.render(),
+        magenta.render_reset(),
+        magenta.render(),
+        magenta.render_reset()
+    );
+
+    let message = Level::Error.message("mismatched types").id("E0308").group(
+        Group::new()
+            .element(
+                Snippet::source(source)
+                    .fold(true)
+                    .origin("$DIR/highlighting.rs")
+                    .annotation(
+                        AnnotationKind::Primary
+                            .span(589..599)
+                            .label("one type is more general than the other"),
+                    )
+                    .annotation(
+                        AnnotationKind::Context
+                            .span(583..588)
+                            .label("arguments to this function are incorrect"),
+                    ),
+            )
+            .element(Level::Note.title(&title)),
+    );
+
+    let renderer = Renderer::styled().anonymized_line_numbers(true);
+    anstream::println!("{}", renderer.render(message));
+}

tests/examples.rs

@@ -26,6 +26,13 @@ fn highlight_source() {
     assert_example(target, expected);
 }
 
+#[test]
+fn highlight_title() {
+    let target = "highlight_title";
+    let expected = snapbox::file!["../examples/highlight_title.svg": TermSvg];
+    assert_example(target, expected);
+}
+
 #[test]
 fn multislice() {
     let target = "multislice";