fix: lowercase qm001 filename

src/rules/qm001.rs

@@ -0,0 +1,137 @@
+use crate::{
+    linter::{RuleViolation, RuleViolationSeverity},
+    rules::{Context, Rule, RuleLinter},
+};
+use comrak::nodes::{Ast, NodeHeading, NodeValue};
+
+pub(crate) struct QM001Linter {
+    context: Context,
+    current_heading_level: u8,
+}
+
+impl QM001Linter {
+    pub fn new(context: Context) -> Self {
+        Self {
+            context,
+            current_heading_level: 0,
+        }
+    }
+}
+
+impl RuleLinter for QM001Linter {
+    fn feed(&mut self, node: &Ast) -> Option<RuleViolation> {
+        if let NodeValue::Heading(NodeHeading { level, setext: _ }) = node.value {
+            if self.current_heading_level > 0 && level as i8 - self.current_heading_level as i8 > 1
+            {
+                return Option::Some(RuleViolation::new(
+                    &QM001,
+                    RuleViolationSeverity::Error,
+                    self.context.file_path.clone(),
+                    &(node.sourcepos),
+                ));
+            }
+            self.current_heading_level = level;
+        }
+        None
+    }
+}
+
+pub const QM001: Rule = Rule {
+    id: "QM001",
+    alias: "heading-increment",
+    tags: &["headings"],
+    description: "Heading levels should only increment by one level at a time",
+    new_linter: |context| Box::new(QM001Linter::new(context)),
+};
+
+#[cfg(test)]
+mod test {
+    use std::path::PathBuf;
+
+    use comrak::{parse_document, Arena, Options};
+
+    use crate::linter::{RuleViolation, Settings};
+    use crate::rules::Context;
+
+    use super::super::RuleLinter;
+    use super::QM001;
+
+    fn lint_content(input: &str, linter: &mut Box<dyn RuleLinter>) -> Vec<RuleViolation> {
+        parse_document(&Arena::new(), input, &Options::default())
+            .descendants()
+            .filter_map(|node| linter.feed(&node.data.borrow()))
+            .collect()
+    }
+
+    fn test_context() -> Context {
+        Context {
+            file_path: PathBuf::from("test.md"),
+            settings: Settings {},
+        }
+    }
+
+    #[test]
+    fn test_positive() {
+        let input = "# Heading level 1
+some text
+`some code`
+## Heading level 2
+some other text
+###### Heading level 6
+foobar
+#### Heading level 4
+### Heading level 3
+";
+
+        let violations = lint_content(input, &mut (QM001.new_linter)(test_context()));
+        assert_eq!(2, violations.len());
+        let mut iter = violations.iter();
+        let range1 = &iter.next().unwrap().location.range;
+        assert_eq!(6, range1.start.line);
+        assert_eq!(1, range1.start.character);
+        assert_eq!(6, range1.end.line);
+        assert_eq!(22, range1.end.character);
+
+        let range2 = &iter.next().unwrap().location.range;
+        assert_eq!(8, range2.start.line);
+        assert_eq!(1, range2.start.character);
+        assert_eq!(8, range2.end.line);
+        assert_eq!(20, range2.end.character);
+    }
+
+    #[test]
+    fn test_negative() {
+        let input = "# Heading level 1
+some text
+`some code`
+## Heading level 2
+some other text
+### Heading level 3
+foobar
+#### Heading level 4
+##### Heading level 5
+###### Heading level 6
+";
+
+        let violations = lint_content(input, &mut (QM001.new_linter)(test_context()));
+        assert_eq!(0, violations.len());
+    }
+
+    #[test]
+    fn test_negative_starts_not_with_level_1() {
+        let input = "## Heading level 2
+some text
+`some code`
+### Heading level 3
+some other text
+#### Heading level 4
+foobar
+##### Heading level 5
+###### Heading level 6
+# level 1
+";
+
+        let violations = lint_content(input, &mut (QM001.new_linter)(test_context()));
+        assert_eq!(0, violations.len());
+    }
+}