elint 0.1.2

Erlang code linter
Documentation 
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//! `case_over_if` lint: prefer case over if.

use super::{Rule, token_span_in_node};
use crate::{BranchContext, Context, Finding};

/// Lint rule that flags every `if` expression.
pub const RULE: Rule = Rule::new(
    "case_over_if",
    include_str!("../../rules/case_over_if/rule.md"),
    check,
);

fn check(_ctx: &Context, branch: &BranchContext) -> Vec<Finding> {
    let mut errors = Vec::new();
    for node in branch.tree.nodes() {
        if node.kind() != erl_parse::SyntaxKind::IfExpr {
            continue;
        }
        if let Some(span) = token_span_in_node(branch, node, |token| {
            matches!(
                token.kind(),
                erl_tokenize::TokenKind::Keyword(erl_tokenize::Keyword::If)
            )
        }) {
            errors.push(Finding {
                span,
                node: node.node_id(),
            });
        }
    }
    errors
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::rules::test_support::findings;

    #[test]
    fn flags_if_expression() {
        let src = "\
-module(t).
foo(N) ->
    if
        N > 0 ->
            positive;
        true ->
            zero
    end.
";
        assert_eq!(findings(check, src), ["if"]);
    }

    #[test]
    fn flags_every_if_expression() {
        let src = "\
-module(t).
foo(N) ->
    if
        N > 0 ->
            positive;
        true ->
            zero
    end,
    if
        true ->
            ok
    end.
";
        assert_eq!(findings(check, src), ["if", "if"]);
    }

    #[test]
    fn ignores_case() {
        let src = "\
-module(t).
foo(N) ->
    case N of
        _ ->
            ok
    end.
";
        assert!(findings(check, src).is_empty());
    }

    #[test]
    fn ng_fixture_has_three_findings() {
        let src = include_str!("../../rules/case_over_if/ng.erl");
        assert_eq!(findings(check, src).len(), 3);
    }

    #[test]
    fn ok_fixture_has_no_findings() {
        let src = include_str!("../../rules/case_over_if/ok.erl");
        assert!(findings(check, src).is_empty());
    }
}