From bdf627ce07e7f0d4dc72eafca3be276c4ed8ca5d Mon Sep 17 00:00:00 2001
From: Marshall Bowers <elliott.codes@gmail.com>
Date: Wed, 29 May 2024 19:23:06 -0400
Subject: [PATCH] rustdoc_to_markdown: Fix code blocks (#12460)

This PR fixes an issue in `rustdoc_to_markdown` with code blocks being
trimmed incorrectly.

We were erroneously popping from the current element stack even if we
didn't push an element onto the stack.

Added test coverage for this case as well, so we don't regress.

Release Notes:

- N/A
---
 Cargo.lock                                    |  1 +
 crates/rustdoc_to_markdown/Cargo.toml         |  1 +
 .../src/markdown_writer.rs                    |  3 +-
 .../src/rustdoc_to_markdown.rs                | 50 +++++++++++++++++++
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 510303fc1e..43a5ac03cc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8640,6 +8640,7 @@ dependencies = [
  "html5ever",
  "indoc",
  "markup5ever_rcdom",
+ "pretty_assertions",
  "regex",
 ]
 
diff --git a/crates/rustdoc_to_markdown/Cargo.toml b/crates/rustdoc_to_markdown/Cargo.toml
index 18bb21f9d9..58a60bc7bf 100644
--- a/crates/rustdoc_to_markdown/Cargo.toml
+++ b/crates/rustdoc_to_markdown/Cargo.toml
@@ -19,3 +19,4 @@ regex.workspace = true
 
 [dev-dependencies]
 indoc.workspace = true
+pretty_assertions.workspace = true
diff --git a/crates/rustdoc_to_markdown/src/markdown_writer.rs b/crates/rustdoc_to_markdown/src/markdown_writer.rs
index cf71982ecb..b48a780c35 100644
--- a/crates/rustdoc_to_markdown/src/markdown_writer.rs
+++ b/crates/rustdoc_to_markdown/src/markdown_writer.rs
@@ -114,9 +114,8 @@ impl MarkdownWriter {
             self.visit_node(child)?;
         }
 
-        self.current_element_stack.pop_back();
-
         if let Some(current_element) = current_element {
+            self.current_element_stack.pop_back();
             self.end_tag(&current_element);
         }
 
diff --git a/crates/rustdoc_to_markdown/src/rustdoc_to_markdown.rs b/crates/rustdoc_to_markdown/src/rustdoc_to_markdown.rs
index dbbafa2c5c..ac34213e2c 100644
--- a/crates/rustdoc_to_markdown/src/rustdoc_to_markdown.rs
+++ b/crates/rustdoc_to_markdown/src/rustdoc_to_markdown.rs
@@ -36,3 +36,53 @@ pub fn convert_rustdoc_to_markdown(mut html: impl Read) -> Result<String> {
 
     Ok(markdown)
 }
+
+#[cfg(test)]
+mod tests {
+    use indoc::indoc;
+    use pretty_assertions::assert_eq;
+
+    use super::*;
+
+    #[test]
+    fn test_code_blocks() {
+        let html = indoc! {r#"
+            <pre class="rust rust-example-rendered"><code><span class="kw">use </span>axum::extract::{Path, Query, Json};
+            <span class="kw">use </span>std::collections::HashMap;
+
+            <span class="comment">// `Path` gives you the path parameters and deserializes them.
+            </span><span class="kw">async fn </span>path(Path(user_id): Path&lt;u32&gt;) {}
+
+            <span class="comment">// `Query` gives you the query parameters and deserializes them.
+            </span><span class="kw">async fn </span>query(Query(params): Query&lt;HashMap&lt;String, String&gt;&gt;) {}
+
+            <span class="comment">// Buffer the request body and deserialize it as JSON into a
+            // `serde_json::Value`. `Json` supports any type that implements
+            // `serde::Deserialize`.
+            </span><span class="kw">async fn </span>json(Json(payload): Json&lt;serde_json::Value&gt;) {}</code></pre>
+        "#};
+        let expected = indoc! {"
+            ```rs
+            use axum::extract::{Path, Query, Json};
+            use std::collections::HashMap;
+
+            // `Path` gives you the path parameters and deserializes them.
+            async fn path(Path(user_id): Path<u32>) {}
+
+            // `Query` gives you the query parameters and deserializes them.
+            async fn query(Query(params): Query<HashMap<String, String>>) {}
+
+            // Buffer the request body and deserialize it as JSON into a
+            // `serde_json::Value`. `Json` supports any type that implements
+            // `serde::Deserialize`.
+            async fn json(Json(payload): Json<serde_json::Value>) {}
+            ```
+        "}
+        .trim();
+
+        assert_eq!(
+            convert_rustdoc_to_markdown(html.as_bytes()).unwrap(),
+            expected
+        )
+    }
+}