feat: add testing macros and unit tests for linters

Add `assert_detected!` and `assert_not_detected!` macros to simplify
writing lint tests, along with initial test coverage for the
unnecessary render result creation linter.

4 files changed, 129 insertions, 0 deletions

diff --git a/mingling_cli/src/lints.rs b/mingling_cli/src/lints.rs
index 5bed483..8fab924 100644
--- a/mingling_cli/src/lints.rs
+++ b/mingling_cli/src/lints.rs
@@ -58,4 +58,22 @@ pub fn run_all_lints(file: &syn::File, source: &str) -> Vec<MlintReport> {
     // Remove allowed reports (sentinel = Help)
     reports.retain(|r| r.level != MlintLevel::Help);
     reports
+}
+
+#[macro_export]
+macro_rules! assert_detected {
+    ($linter:expr, $ast_type:ty => $code:tt) => {
+        // Parse the string into a syn::ItemFn
+        let ast: $ast_type = syn::parse_str(&stringify!($code)).unwrap();
+        assert!(!$linter(ast, &stringify!($code).to_string()).is_empty());
+    };
+}
+
+#[macro_export]
+macro_rules! assert_not_detected {
+    ($linter:expr, $ast_type:ty => $code:tt) => {
+        // Parse the string into a syn::ItemFn
+        let ast: $ast_type = syn::parse_str(&stringify!($code)).unwrap();
+        assert!($linter(ast, &stringify!($code).to_string()).is_empty());
+    };
 }
\ No newline at end of file
diff --git a/mingling_cli/src/lints/template_linter.rs b/mingling_cli/src/lints/template_linter.rs
index 4ea2f94..271aa0c 100644
--- a/mingling_cli/src/lints/template_linter.rs
+++ b/mingling_cli/src/lints/template_linter.rs
@@ -46,3 +46,11 @@ pub fn linter(_ast: syn::ItemFn, _source: &str) -> Vec<MlintReport> {
     //                               | syn::ItemUnion
     vec![]
 }
+
+#[cfg(test)]
+mod lint_test {
+    use crate::{assert_detected, assert_not_detected};
+
+    #[test]
+    fn test() {}
+}
diff --git a/mingling_cli/src/lints/unnecessary_render_result_creation.rs b/mingling_cli/src/lints/unnecessary_render_result_creation.rs
index aa0f4a6..06c47d9 100644
--- a/mingling_cli/src/lints/unnecessary_render_result_creation.rs
+++ b/mingling_cli/src/lints/unnecessary_render_result_creation.rs
@@ -172,3 +172,88 @@ fn check_stmt_usage(stmt: &syn::Stmt, r_name: &str, print_count: &mut usize) ->
     let s = format!("{stmt:#?}");
     !s.contains(&format!("\"{r_name}\""))
 }
+
+#[cfg(test)]
+mod lint_test {
+    use crate::{assert_detected, assert_not_detected};
+
+    #[test]
+    fn test_detected_render_result_new() {
+        assert_detected!(super::linter, syn::ItemFn => {
+            #[renderer]
+            fn render_somesthing(_: Prev) -> RenderResult {
+                let mut r = RenderResult::new();
+                r_println!(r, "");
+                r
+            }
+        });
+    }
+
+    #[test]
+    fn test_detected_render_result_default() {
+        assert_detected!(super::linter, syn::ItemFn => {
+            #[renderer]
+            fn render_somesthing(_: Prev) -> RenderResult {
+                let mut r = RenderResult::default();
+                r_println!(r, "");
+                r
+            }
+        });
+    }
+
+    #[test]
+    fn test_detected_render_result_from() {
+        assert_detected!(super::linter, syn::ItemFn => {
+            #[renderer]
+            fn render_somesthing(_: Prev) -> RenderResult {
+                let mut r = RenderResult::from("Hello".to_string());
+                r_println!(r, "");
+                r
+            }
+        });
+    }
+
+    #[test]
+    fn test_not_detected_with_other_function_call() {
+        assert_not_detected!(super::linter, syn::ItemFn => {
+            #[renderer]
+            fn render_somesthing(_: Prev) -> RenderResult {
+                let mut r = RenderResult::new();
+                r_println!(r, "");
+                other(&mut r);
+                r
+            }
+        });
+    }
+
+    #[test]
+    fn test_not_detected_without_renderer_attr() {
+        assert_not_detected!(super::linter, syn::ItemFn => {
+            fn render_somesthing(_: Prev) -> RenderResult {
+                let mut r = RenderResult::new();
+                r_println!(r, "");
+                r
+            }
+        });
+    }
+
+    #[test]
+    fn test_not_detected_with_buffer_attr() {
+        assert_not_detected!(super::linter, syn::ItemFn => {
+            #[::mingling::macros::renderer(::mingling::macros::buffer)]
+            fn render_somesthing(_: Prev) {
+                r_println!("");
+            }
+        });
+    }
+
+    #[test]
+    fn test_not_detected_with_buffer_attr_fully_qualified() {
+        assert_not_detected!(super::linter, syn::ItemFn => {
+            #[::mingling::macros::renderer(::mingling::macros::buffer)]
+            fn render_somesthing(_: Prev) {
+                r_println!("");
+            }
+        });
+    }
+}
diff --git a/mingling_cli/tmpls/lints.tmpl b/mingling_cli/tmpls/lints.tmpl
index 7507f98..fae1126 100644
--- a/mingling_cli/tmpls/lints.tmpl
+++ b/mingling_cli/tmpls/lints.tmpl
@@ -50,6 +50,24 @@ pub fn run_all_lints(file: &syn::File, source: &str) -> Vec<MlintReport> {
     reports
 }
 
+#[macro_export]
+macro_rules! assert_detected {
+    ($linter:expr, $ast_type:ty => $code:tt) => {
+        // Parse the string into a syn::ItemFn
+        let ast: $ast_type = syn::parse_str(&stringify!($code)).unwrap();
+        assert!(!$linter(ast, &stringify!($code).to_string()).is_empty());
+    };
+}
+
+#[macro_export]
+macro_rules! assert_not_detected {
+    ($linter:expr, $ast_type:ty => $code:tt) => {
+        // Parse the string into a syn::ItemFn
+        let ast: $ast_type = syn::parse_str(&stringify!($code)).unwrap();
+        assert!($linter(ast, &stringify!($code).to_string()).is_empty());
+    };
+}
+
 @@@ >>> impls
 mod <<<mod_name>>>;
 pub use <<<mod_name>>>::linter as <<<mod_name>>>;