3 files changed, 77 insertions, 24 deletions

diff --git a/bin/tests/data/faster_groupby.nix b/bin/tests/data/faster_groupby.nix
new file mode 100644
index 0000000..30d1031
--- /dev/null
+++ b/bin/tests/data/faster_groupby.nix
@@ -0,0 +1,15 @@
+{
+  # trivial case
+  _ = lib.groupBy (x: if x > 2 then "big" else "small") [ 1 2 3 4 5 ];
+
+  # offer lint heuristically on this too
+  _ = nixpkgs.lib.groupBy (x: if x > 2 then "big" else "small") [ 1 2 3 4 5 ];
+
+  # do not lint on `builtins`
+  _ = builtins.groupBy (x: x.name) [
+    { name = "foo"; idx = 1; }
+    { name = "foo"; idx = 2; }
+    { name = "bar"; idx = 1; }
+    { name = "bar"; idx = 2; }
+  ];
+}
diff --git a/bin/tests/main.rs b/bin/tests/main.rs
index de5266f..991c876 100644
--- a/bin/tests/main.rs
+++ b/bin/tests/main.rs
@@ -1,31 +1,48 @@
+use lib::session::{SessionInfo, Version};
+
+macro_rules! session_info {
+    ($version:expr) => {{
+        let v: Version = $version.parse().unwrap();
+        SessionInfo::from_version(v)
+    }};
+}
+
 mod util {
     #[macro_export]
     macro_rules! test_lint {
-        ($($tname:ident),*,) => {
-            test_lint!($($tname),*);
+        ($tname:ident => $sess:expr, $($tail:tt)*) => {
+            test_lint!($tname => $sess);
+            test_lint!($($tail)*);
+        };
+        ($tname:ident, $($tail:tt)*) => {
+                test_lint!($tname);
+                test_lint!($($tail)*);
+        };
+        ($tname:ident) => {
+            test_lint!($tname => session_info!("nix (Nix) 2.5"));
         };
-        ($($tname:ident),*) => {
-            $(
-                #[test]
-                fn $tname() {
-                    use statix::{config::OutFormat, traits::WriteDiagnostic, lint};
-                    use vfs::ReadOnlyVfs;
-
-                    let file_path = concat!("data/", stringify!($tname), ".nix");
-                    let contents = include_str!(concat!("data/", stringify!($tname), ".nix"));
-
-                    let vfs = ReadOnlyVfs::singleton(file_path, contents.as_bytes());
-
-                    let mut buffer = Vec::new();
-                    vfs.iter().map(lint::lint).for_each(|r| {
-                        buffer.write(&r, &vfs, OutFormat::StdErr).unwrap();
-                    });
-
-                    let stripped = strip_ansi_escapes::strip(&buffer).unwrap();
-                    let out =  std::str::from_utf8(&stripped).unwrap();
-                    insta::assert_snapshot!(&out);
-                }
-            )*
+        ($tname:ident => $sess:expr) => {
+            #[test]
+            fn $tname() {
+                use statix::{config::OutFormat, traits::WriteDiagnostic, lint};
+                use vfs::ReadOnlyVfs;
+
+                let file_path = concat!("data/", stringify!($tname), ".nix");
+                let contents = include_str!(concat!("data/", stringify!($tname), ".nix"));
+
+                let vfs = ReadOnlyVfs::singleton(file_path, contents.as_bytes());
+
+                let session = $sess;
+
+                let mut buffer = Vec::new();
+                vfs.iter().map(|entry| lint::lint(entry, &session)).for_each(|r| {
+                    buffer.write(&r, &vfs, OutFormat::StdErr).unwrap();
+                });
+
+                let stripped = strip_ansi_escapes::strip(&buffer).unwrap();
+                let out =  std::str::from_utf8(&stripped).unwrap();
+                insta::assert_snapshot!(&out);
+            }
         };
     }
 }
@@ -44,4 +61,5 @@ test_lint! {
     unquoted_uri,
     deprecated_is_null,
     empty_inherit,
+    faster_groupby => session_info!("nix (Nix) 2.5")
 }
diff --git a/bin/tests/snapshots/main__faster_groupby.snap b/bin/tests/snapshots/main__faster_groupby.snap
new file mode 100644
index 0000000..6ff3380
--- /dev/null
+++ b/bin/tests/snapshots/main__faster_groupby.snap
@@ -0,0 +1,20 @@
+---
+source: bin/tests/main.rs
+expression: "&out"
+
+---
+[W15] Warning: Found lib.groupBy
+   ╭─[data/faster_groupby.nix:3:7]
+   │
+ 3 │   _ = lib.groupBy (x: if x > 2 then "big" else "small") [ 1 2 3 4 5 ];
+   ·       ─────┬─────  
+   ·            ╰─────── Prefer builtins.groupBy over lib.groupBy
+───╯
+[W15] Warning: Found lib.groupBy
+   ╭─[data/faster_groupby.nix:6:7]
+   │
+ 6 │   _ = nixpkgs.lib.groupBy (x: if x > 2 then "big" else "small") [ 1 2 3 4 5 ];
+   ·       ─────────┬─────────  
+   ·                ╰─────────── Prefer builtins.groupBy over nixpkgs.lib.groupBy
+───╯
+