test: Add a test for keeping lines with no annotations

Author: Muscraft

examples/struct_name_as_context.rs

@@ -0,0 +1,31 @@
+use annotate_snippets::{AnnotationKind, Group, Level, Renderer, Snippet};
+fn main() {
+    let source = r#"struct S {
+    field1: usize,
+    field2: usize,
+    field3: usize,
+    field4: usize,
+    fn foo() {},
+    field6: usize,
+}
+"#;
+    let message =
+        &[
+            Group::with_title(
+                Level::ERROR.title("functions are not allowed in struct definitions"),
+            )
+            .element(
+                Snippet::source(source)
+                    .path("$DIR/struct_name_as_context.rs")
+                    .annotation(AnnotationKind::Primary.span(91..102)),
+            )
+            .element(
+                Level::HELP.message(
+                    "unlike in C++, Java, and C#, functions are declared in `impl` blocks",
+                ),
+            ),
+        ];
+
+    let renderer = Renderer::styled();
+    anstream::println!("{}", renderer.render(message));
+}

examples/struct_name_as_context.svg

@@ -70,6 +70,13 @@ fn multislice() {
     assert_example(target, expected);
 }
 
+#[test]
+fn struct_name_as_context() {
+    let target = "struct_name_as_context";
+    let expected = snapbox::file!["../examples/struct_name_as_context.svg": TermSvg];
+    assert_example(target, expected);
+}
+
 #[track_caller]
 fn assert_example(target: &str, expected: snapbox::Data) {
     let bin_path = snapbox::cmd::compile_example(target, ["--features=testing-colors"]).unwrap();

tests/examples.rs

@@ -3005,3 +3005,67 @@ LL |         .sum::<_>() //~ ERROR type annotations needed
     let renderer = Renderer::plain().anonymized_line_numbers(true);
     assert_data_eq!(renderer.render(input), expected);
 }
+
+#[test]
+fn keep_lines1() {
+    let source = r#"
+cargo
+fuzzy
+pizza
+jumps
+crazy
+quack
+zappy
+"#;
+
+    let input_new = &[Group::with_title(
+        Level::ERROR
+            .title("the size for values of type `T` cannot be known at compilation time")
+            .id("E0277"),
+    )
+    .element(
+        Snippet::source(source)
+            .line_start(11)
+            .annotation(AnnotationKind::Primary.span(1..6)),
+    )];
+    let expected = str![[r#"
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+   |
+12 | cargo
+   | ^^^^^
+"#]];
+    let renderer = Renderer::plain();
+    assert_data_eq!(renderer.render(input_new), expected);
+}
+
+#[test]
+fn keep_lines2() {
+    let source = r#"
+cargo
+fuzzy
+pizza
+jumps
+crazy
+quack
+zappy
+"#;
+
+    let input_new = &[Group::with_title(
+        Level::ERROR
+            .title("the size for values of type `T` cannot be known at compilation time")
+            .id("E0277"),
+    )
+    .element(
+        Snippet::source(source)
+            .line_start(11)
+            .annotation(AnnotationKind::Primary.span(1..6)),
+    )];
+    let expected = str![[r#"
+error[E0277]: the size for values of type `T` cannot be known at compilation time
+   |
+12 | cargo
+   | ^^^^^
+"#]];
+    let renderer = Renderer::plain();
+    assert_data_eq!(renderer.render(input_new), expected);
+}