inputs: handle deeply nested inputs

Handle follows inputs of the form:
`
inputs = {
  nixpkgs = {
    follows = "nixpkgs";
  };
};
`

Author: a-kenji

src/walk/inputs.rs

@@ -718,22 +718,53 @@ fn handle_url_attr(
         && SyntaxKind::NODE_ATTR_SET == attr_set.kind()
     {
         for nested_attr in attr_set.children() {
-            let is_follows = nested_attr
-                .first_child()
-                .unwrap()
-                .first_child()
-                .unwrap()
-                .next_sibling()
-                .unwrap();
-
-            if is_follows.to_string() == "follows" {
-                let id = is_follows.prev_sibling().unwrap();
-                let follows = nested_attr.first_child().unwrap().next_sibling().unwrap();
-                let input =
-                    Input::with_url(id.to_string(), follows.to_string(), follows.text_range());
-                insert_with_ctx(inputs, id.to_string(), input, ctx);
-                if should_remove_nested_input(change, ctx, &follows.to_string()) {
-                    return Some(empty_node());
+            let Some(attrpath) = nested_attr.first_child() else {
+                continue;
+            };
+            let Some(first_ident) = attrpath.first_child() else {
+                continue;
+            };
+
+            if let Some(follows_ident) = first_ident.next_sibling() {
+                // Flat attrpath style: `nixpkgs.follows = "nixpkgs"`
+                if follows_ident.to_string() == "follows" {
+                    let id = &first_ident;
+                    let Some(follows) = attrpath.next_sibling() else {
+                        continue;
+                    };
+                    let input =
+                        Input::with_url(id.to_string(), follows.to_string(), follows.text_range());
+                    insert_with_ctx(inputs, id.to_string(), input, ctx);
+                    if should_remove_nested_input(change, ctx, &follows.to_string()) {
+                        return Some(empty_node());
+                    }
+                }
+            } else if let Some(value_node) = attrpath.next_sibling()
+                && SyntaxKind::NODE_ATTR_SET == value_node.kind()
+            {
+                // Deeply nested attrset style: `nixpkgs = { follows = "nixpkgs"; }`
+                let id = &first_ident;
+                for inner_attr in value_node.children() {
+                    let Some(inner_path) = inner_attr.first_child() else {
+                        continue;
+                    };
+                    let Some(inner_ident) = inner_path.first_child() else {
+                        continue;
+                    };
+                    if inner_ident.to_string() == "follows" {
+                        let Some(follows) = inner_path.next_sibling() else {
+                            continue;
+                        };
+                        let input = Input::with_url(
+                            id.to_string(),
+                            follows.to_string(),
+                            follows.text_range(),
+                        );
+                        insert_with_ctx(inputs, id.to_string(), input, ctx);
+                        if should_remove_nested_input(change, ctx, &follows.to_string()) {
+                            return Some(empty_node());
+                        }
+                    }
                 }
             }
         }

tests/cli.rs

@@ -61,6 +61,7 @@ fn stderr_path_filters(settings: &mut insta::Settings) {
 #[case("one_level_nesting_flat")]
 #[case("flat_nested_flat")]
 #[case("first_nested_node")]
+#[case("deeply_nested_inputs")]
 #[case("follows_cycle")]
 fn test_list(#[case] fixture: &str) {
     let mut settings = insta::Settings::clone_current();
@@ -104,6 +105,7 @@ fn test_list_format(#[case] fixture: &str, #[case] format: &str) {
 #[case("first_nested_node", "vmsh", "github:mic92/vmsh")]
 #[case("comments_before_brace", "vmsh", "github:mic92/vmsh")]
 #[case("all_blanks", "vmsh", "github:mic92/vmsh")]
+#[case("deeply_nested_inputs", "vmsh", "github:mic92/vmsh")]
 fn test_add(#[case] fixture: &str, #[case] id: &str, #[case] uri: &str) {
     let mut settings = insta::Settings::clone_current();
     path_redactions(&mut settings);
@@ -221,6 +223,7 @@ fn test_add_infer_id(#[case] fixture: &str) {
 #[case("flat_nested_flat", "nixpkgs")]
 #[case("first_nested_node", "nixpkgs")]
 #[case("comments_before_brace", "nixpkgs")]
+#[case("deeply_nested_inputs", "nixpkgs")]
 #[case("root", "rust-overlay")]
 #[case("outputs_leading_comma_remove_first", "nixpkgs-unstable")]
 fn test_remove(#[case] fixture: &str, #[case] id: &str) {
@@ -261,6 +264,7 @@ fn test_remove(#[case] fixture: &str, #[case] id: &str) {
 )]
 #[case("flat_nested_flat", "nixpkgs", "github:nixos/nixpkgs/nixos-24.05")]
 #[case("first_nested_node", "nixpkgs", "github:nixos/nixpkgs/nixos-24.05")]
+#[case("deeply_nested_inputs", "nixpkgs", "github:nixos/nixpkgs/nixos-24.05")]
 fn test_change(#[case] fixture: &str, #[case] id: &str, #[case] uri: &str) {
     let mut settings = insta::Settings::clone_current();
     path_redactions(&mut settings);

tests/fixtures/deeply_nested_inputs.flake.nix

@@ -0,0 +1,18 @@
+{
+  description = "Deeply nested inputs attrset";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+    disko = {
+      url = "github:nix-community/disko";
+      inputs = {
+        nixpkgs = {
+          follows = "nixpkgs";
+        };
+      };
+    };
+  };
+
+  outputs = _: { };
+}

tests/snapshots/cli__add@deeply_nested_inputs_vmsh.snap

@@ -0,0 +1,29 @@
+---
+source: tests/cli.rs
+info:
+  program: flake-edit
+  args:
+    - "--flake"
+    - "[FIXTURES]/deeply_nested_inputs.flake.nix"
+    - "--diff"
+    - add
+    - vmsh
+    - "github:mic92/vmsh"
+  env:
+    NO_COLOR: "1"
+---
+success: true
+exit_code: 0
+----- stdout -----
+--- original
++++ modified
+@@ -12,6 +12,7 @@
+         };
+       };
+     };
++    vmsh.url = "github:mic92/vmsh";
+   };
+
+   outputs = _: { };
+
+----- stderr -----

tests/snapshots/cli__change@deeply_nested_inputs_nixpkgs.snap

@@ -0,0 +1,30 @@
+---
+source: tests/cli.rs
+info:
+  program: flake-edit
+  args:
+    - "--flake"
+    - "[FIXTURES]/deeply_nested_inputs.flake.nix"
+    - "--diff"
+    - change
+    - nixpkgs
+    - "github:nixos/nixpkgs/nixos-24.05"
+  env:
+    NO_COLOR: "1"
+---
+success: true
+exit_code: 0
+----- stdout -----
+--- original
++++ modified
+@@ -2,7 +2,7 @@
+   description = "Deeply nested inputs attrset";
+
+   inputs = {
+-    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
++    nixpkgs.url = "github:nixos/nixpkgs/nixos-24.05";
+
+     disko = {
+       url = "github:nix-community/disko";
+
+----- stderr -----

tests/snapshots/cli__list@deeply_nested_inputs.snap

@@ -0,0 +1,19 @@
+---
+source: tests/cli.rs
+info:
+  program: flake-edit
+  args:
+    - "--flake"
+    - "[FIXTURES]/deeply_nested_inputs.flake.nix"
+    - list
+  env:
+    NO_COLOR: "1"
+---
+success: true
+exit_code: 0
+----- stdout -----
+· disko - "github:nix-community/disko"
+     nixpkgs => "nixpkgs"
+· nixpkgs - "github:nixos/nixpkgs/nixos-unstable"
+
+----- stderr -----

tests/snapshots/cli__remove@deeply_nested_inputs_nixpkgs.snap

@@ -0,0 +1,28 @@
+---
+source: tests/cli.rs
+info:
+  program: flake-edit
+  args:
+    - "--flake"
+    - "[FIXTURES]/deeply_nested_inputs.flake.nix"
+    - "--diff"
+    - rm
+    - nixpkgs
+  env:
+    NO_COLOR: "1"
+---
+success: true
+exit_code: 0
+----- stdout -----
+--- original
++++ modified
+@@ -2,7 +2,6 @@
+   description = "Deeply nested inputs attrset";
+
+   inputs = {
+-    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+     disko = {
+       url = "github:nix-community/disko";
+
+----- stderr -----

tests/snapshots/walker__walker_list_inputs@deeply_nested_inputs.snap

@@ -0,0 +1,26 @@
+---
+source: tests/walker.rs
+expression: walker.inputs
+info:
+  flake_nix: ""
+  changes: []
+---
+disko:
+  id: disko
+  flake: true
+  url: "\"github:nix-community/disko\""
+  follows:
+    - Indirect:
+        - nixpkgs
+        - "\"nixpkgs\""
+  range:
+    start: 148
+    end: 176
+nixpkgs:
+  id: nixpkgs
+  flake: true
+  url: "\"github:nixos/nixpkgs/nixos-unstable\""
+  follows: []
+  range:
+    start: 82
+    end: 119

tests/walker.rs

@@ -13,6 +13,7 @@ use rstest::rstest;
 #[case("completely_flat_toplevel_alt")]
 #[case("one_level_nesting_flat")]
 #[case("flat_nested_flat")]
+#[case("deeply_nested_inputs")]
 fn test_walker_list_inputs(#[case] fixture: &str) {
     let content = load_flake(fixture);
     let mut walker = Walker::new(&content);