Add new lint for space in Headers

README.md

@@ -74,6 +74,7 @@ error[preamble-order]: preamble header `description` must come after `title`
 | `markdown-refs`                     | ERCs are referenced using ERC-X, while other proposals use EIP-X.                             |
 | `markdown-rel-links`                | All URLs in the page are relative.                                                            |
 | `markdown-req-section`              | Required sections are present in the body of the proposal.                                    |
+| `markdown-headings-space`           | Headers have a space after the leading '#' characters                                           |
 | `preamble-author`                   | The author header is correctly formatted, and there is at least one GitHub user listed.       |
 | `preamble-date-created`             | The `created` header is a date.                                                               |
 | `preamble-date-last-call-deadline`  | The `last-call-deadline` header is a date.                                                    |

eipw-lint/src/lib.rs

@@ -457,6 +457,10 @@ pub fn default_lints_enum() -> impl Iterator<Item = (&'static str, DefaultLint<&
                 ),
             }),
         ),
+        (
+            "markdown-headings-space",
+            MarkdownHeadingsSpace(markdown::HeadingsSpace{}),
+        )
     ]
     .into_iter()
 }

eipw-lint/src/lints/known_lints.rs

@@ -68,6 +68,7 @@ pub enum DefaultLint<S> {
     MarkdownSectionRequired {
         sections: markdown::SectionRequired<S>,
     },
+    MarkdownHeadingsSpace(markdown::HeadingsSpace),
 }
 
 impl<S> DefaultLint<S>
@@ -110,6 +111,7 @@ where
             Self::MarkdownRelativeLinks(l) => Box::new(l),
             Self::MarkdownSectionOrder { sections } => Box::new(sections),
             Self::MarkdownSectionRequired { sections } => Box::new(sections),
+            Self::MarkdownHeadingsSpace(l) => Box::new(l),
         }
     }
 }
@@ -148,6 +150,7 @@ where
             Self::MarkdownRelativeLinks(l) => l,
             Self::MarkdownSectionOrder { sections } => sections,
             Self::MarkdownSectionRequired { sections } => sections,
+            Self::MarkdownHeadingsSpace(l) => l,
         }
     }
 }
@@ -278,6 +281,7 @@ where
             Self::MarkdownSectionRequired { sections } => DefaultLint::MarkdownSectionRequired {
                 sections: markdown::SectionRequired(sections.0.iter().map(AsRef::as_ref).collect()),
             },
+            Self::MarkdownHeadingsSpace(l) => DefaultLint::MarkdownHeadingsSpace(l.clone()),
         }
     }
 }

eipw-lint/src/lints/markdown.rs

@@ -4,6 +4,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+pub mod headings_space;
 pub mod html_comments;
 pub mod json_schema;
 pub mod link_first;
@@ -14,6 +15,7 @@ pub mod relative_links;
 pub mod section_order;
 pub mod section_required;
 
+pub use self::headings_space::HeadingsSpace;
 pub use self::html_comments::HtmlComments;
 pub use self::json_schema::JsonSchema;
 pub use self::link_first::LinkFirst;

eipw-lint/src/lints/markdown/headings_space.rs

@@ -0,0 +1,82 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+use annotate_snippets::snippet::{Annotation, Slice, Snippet};
+
+use annotate_snippets::snippet::SourceAnnotation;
+use comrak::nodes::Ast;
+use comrak::nodes::NodeValue;
+use regex::Regex;
+
+use crate::lints::{Context, Error, Lint};
+
+use serde::{Deserialize, Serialize};
+
+use std::fmt::Debug;
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct HeadingsSpace;
+
+impl Lint for HeadingsSpace {
+    fn lint<'a>(&self, slug: &'a str, ctx: &Context<'a, '_>) -> Result<(), Error> {
+        // Match for text nodes starting with leading '#' chars (upto 6)
+        // Markdown does not recognise these nodes as valid Headings without the space
+        let heading_pattern = Regex::new("^#{1,6}").unwrap();
+        let invalid_headings: Vec<_> = ctx
+            .body()
+            .descendants()
+            .filter_map(|node| match &*node.data.borrow() {
+                // Collect all matching Text nodes
+                Ast {
+                    value: NodeValue::Text(text),
+                    ..
+                } => {
+                    if let Some(matched_text) = heading_pattern.find(text) {
+                        let heading_level = matched_text.end();
+                        Some((
+                            text.clone(),
+                            node.data.borrow().sourcepos.start.line,
+                            heading_level,
+                        ))
+                    } else {
+                        None
+                    }
+                }
+                _ => None,
+            })
+            .collect();
+
+        let slices: Vec<_> = invalid_headings
+            .iter()
+            .map(|(text, line_start, heading_level)| Slice {
+                line_start: *line_start,
+                origin: ctx.origin(),
+                source: text,
+                fold: false,
+                annotations: vec![SourceAnnotation {
+                    annotation_type: ctx.annotation_type(),
+                    label: "space required here",
+                    range: (*heading_level - 1, *heading_level),
+                }],
+            })
+            .collect();
+
+        if !slices.is_empty() {
+            ctx.report(Snippet {
+                title: Some(Annotation {
+                    id: Some(slug),
+                    annotation_type: ctx.annotation_type(),
+                    label: Some("Space missing in header"),
+                }),
+                footer: vec![],
+                slices,
+                opt: Default::default(),
+            })?;
+        }
+
+        Ok(())
+    }
+}

eipw-lint/tests/lint_markdown_headings_space.rs

@@ -0,0 +1,71 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+use eipw_lint::lints::markdown::HeadingsSpace;
+use eipw_lint::reporters::Text;
+use eipw_lint::Linter;
+
+#[tokio::test]
+async fn normal_headings() {
+    let src = r#"---
+header: value1
+---
+
+##Banana
+####Mango
+"#;
+
+    let reports = Linter::<Text<String>>::default()
+        .clear_lints()
+        .deny("markdown-headings-space", HeadingsSpace {})
+        .check_slice(None, src)
+        .run()
+        .await
+        .unwrap()
+        .into_inner();
+
+    assert_eq!(
+        reports,
+        r#"error[markdown-headings-space]: Space missing in header
+  |
+5 | ##Banana
+  |  ^ space required here
+  |
+6 | ####Mango
+  |    ^ space required here
+  |
+"#
+    );
+}
+
+#[tokio::test]
+async fn abnormal_heading() {
+    let src = r#"---
+header: value1
+---
+
+##B#an#ana
+"#;
+
+    let reports = Linter::<Text<String>>::default()
+        .clear_lints()
+        .deny("markdown-headings-space", HeadingsSpace {})
+        .check_slice(None, src)
+        .run()
+        .await
+        .unwrap()
+        .into_inner();
+
+    assert_eq!(
+        reports,
+        r#"error[markdown-headings-space]: Space missing in header
+  |
+5 | ##B#an#ana
+  |  ^ space required here
+  |
+"#
+    );
+}