Add integration tests for line comment continuation

Author: the-mikedavis

helix-term/tests/test/commands/insert.rs

@@ -51,3 +51,71 @@ async fn insert_newline_trim_trailing_whitespace() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn insert_newline_continue_line_comment() -> anyhow::Result<()> {
+    // `insert_newline` continues a single line comment
+    test((
+        indoc! {"\
+            // Hello world!#[|
+            ]#
+            "},
+        ":lang rust<ret>i<ret>",
+        indoc! {"\
+            // Hello world!
+            // #[|
+            ]#
+            "},
+    ))
+    .await?;
+
+    // The comment is not continued if the cursor is before the comment token. (Note that we
+    // are entering insert-mode with `I`.)
+    test((
+        indoc! {"\
+            // Hello world!#[|
+            ]#
+            "},
+        ":lang rust<ret>I<ret>",
+        indoc! {"\
+            \n#[/|]#/ Hello world!
+            "},
+    ))
+    .await?;
+
+    // `insert_newline` again clears the whitespace on the first continued comment and continues
+    // the comment again.
+    test((
+        indoc! {"\
+            // Hello world!
+            // #[|
+            ]#
+            "},
+        ":lang rust<ret>i<ret>",
+        indoc! {"\
+            // Hello world!
+            //
+            // #[|
+            ]#
+            "},
+    ))
+    .await?;
+
+    // Line comment continuation and trailing whitespace is also trimmed when using
+    // `insert_newline` in the middle of a comment.
+    test((
+        indoc! {"\
+            //·hello····#[|·]#····world
+            "}
+        .replace('·', " "),
+        ":lang rust<ret>i<ret>",
+        indoc! {"\
+            //·hello
+            //·#[|·]#····world
+            "}
+        .replace('·', " "),
+    ))
+    .await?;
+
+    Ok(())
+}