feat(nodejs): Add `expected_version` variable (#5081)

* add `expected_version` variable to `nodejs`

* show comparison symbols with `expected_version`

* documentation, formatting, more tests

* Remapped `engines_version` to $version

* Added better descriptions to docs

* Update docs/config/README.md

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

* Removed clone from `nodejs`, formatting

* refactored function calls

* rewrote `engines_version` formatter

* Moved Lazy variables into maps

---------

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

2 files changed, 104 insertions, 12 deletions

diff --git a/docs/config/README.md b/docs/config/README.md
index d75c805d3..5050631c9 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -2859,11 +2859,12 @@ By default the module will be shown if any of the following conditions are met:
 
 ### Variables
 
-| Variable | Example    | Description                          |
-| -------- | ---------- | ------------------------------------ |
-| version  | `v13.12.0` | The version of `node`                |
-| symbol   |            | Mirrors the value of option `symbol` |
-| style\*  |            | Mirrors the value of option `style`  |
+| Variable        | Example    | Description                                                                                                                                               |
+| --------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| version         | `v13.12.0` | The version of `node`                                                                                                                                     |
+| engines_version | `>=12.0.0` | `node` version requirement as set in the engines property of `package.json`. Will only show if the version requirement does not match the `node` version. |
+| symbol          |            | Mirrors the value of option `symbol`                                                                                                                      |
+| style\*         |            | Mirrors the value of option `style`                                                                                                                       |
 
 *: This variable can only be used as a part of a style string
 
diff --git a/src/modules/nodejs.rs b/src/modules/nodejs.rs
index 295dc71ea..bf319fcfd 100644
--- a/src/modules/nodejs.rs
+++ b/src/modules/nodejs.rs
@@ -35,6 +35,8 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
             .exec_cmd("node", &["--version"])
             .map(|cmd| cmd.stdout)
     });
+    let engines_version = Lazy::new(|| get_engines_version(context));
+
     let parsed = StringFormatter::new(config.format).and_then(|formatter| {
         formatter
             .map_meta(|var, _| match var {
@@ -43,9 +45,11 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
             })
             .map_style(|variable| match variable {
                 "style" => {
-                    let engines_version = get_engines_version(context);
-                    let in_engines_range =
-                        check_engines_version(nodejs_version.as_deref(), engines_version);
+                    let in_engines_range = check_engines_version(
+                        nodejs_version.as_deref(),
+                        engines_version.as_deref(),
+                    );
+
                     if in_engines_range {
                         Some(Ok(config.style))
                     } else {
@@ -56,7 +60,7 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
             })
             .map(|variable| match variable {
                 "version" => {
-                    let version = nodejs_version
+                    let node_ver = nodejs_version
                         .deref()
                         .as_ref()?
                         .trim_start_matches('v')
@@ -64,11 +68,20 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
 
                     VersionFormatter::format_module_version(
                         module.get_name(),
-                        version,
+                        node_ver,
                         config.version_format,
                     )
                     .map(Ok)
                 }
+                "engines_version" => {
+                    let in_engines_range = check_engines_version(
+                        nodejs_version.as_deref(),
+                        engines_version.as_deref(),
+                    );
+                    let eng_ver = engines_version.as_deref()?.to_string();
+
+                    (!in_engines_range).then_some(Ok(eng_ver))
+                }
                 _ => None,
             })
             .parse(None, Some(context))
@@ -89,16 +102,19 @@ fn get_engines_version(context: &Context) -> Option<String> {
     let json_str = context.read_file_from_pwd("package.json")?;
     let package_json: json::Value = json::from_str(&json_str).ok()?;
     let raw_version = package_json.get("engines")?.get("node")?.as_str()?;
+
     Some(raw_version.to_string())
 }
 
-fn check_engines_version(nodejs_version: Option<&str>, engines_version: Option<String>) -> bool {
+fn check_engines_version(nodejs_version: Option<&str>, engines_version: Option<&str>) -> bool {
     let (Some(nodejs_version), Some(engines_version)) = (nodejs_version, engines_version) else {
         return true;
     };
-    let Ok(r) = VersionReq::parse(&engines_version) else {
+
+    let Ok(r) = VersionReq::parse(engines_version) else {
         return true;
     };
+
     let re = Regex::new(r"\d+\.\d+\.\d+").unwrap();
     let version = re
         .captures(nodejs_version)
@@ -106,6 +122,7 @@ fn check_engines_version(nodejs_version: Option<&str>, engines_version: Option<S
         .get(0)
         .unwrap()
         .as_str();
+
     let v = match Version::parse(version) {
         Ok(v) => v,
         Err(_e) => return true,
@@ -269,6 +286,80 @@ mod tests {
         assert_eq!(expected, actual);
         dir.close()
     }
+
+    #[test]
+    fn show_expected_version_when_engines_does_not_match() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        let mut file = File::create(dir.path().join("package.json"))?;
+        file.write_all(
+            b"{
+            \"engines\":{
+                \"node\":\"<=11.0.0\"
+            }
+        }",
+        )?;
+        file.sync_all()?;
+
+        let actual = ModuleRenderer::new("nodejs")
+            .path(dir.path())
+            .config(toml::toml! {
+                [nodejs]
+                format = "via [$symbol($version )($engines_version )]($style)"
+            })
+            .collect();
+        let expected = Some(format!(
+            "via {}",
+            Color::Red.bold().paint(" v12.0.0 <=11.0.0 ")
+        ));
+
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn do_not_show_expected_version_if_engines_match() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        let mut file = File::create(dir.path().join("package.json"))?;
+        file.write_all(
+            b"{
+            \"engines\":{
+                \"node\":\">=12.0.0\"
+            }
+        }",
+        )?;
+        file.sync_all()?;
+
+        let actual = ModuleRenderer::new("nodejs")
+            .path(dir.path())
+            .config(toml::toml! [
+                [nodejs]
+                format = "via [$symbol($version )($engines_version )]($style)"
+            ])
+            .collect();
+        let expected = Some(format!("via {}", Color::Green.bold().paint(" v12.0.0 ")));
+
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn do_not_show_expected_version_if_no_set_engines_version() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join("package.json"))?.sync_all()?;
+
+        let actual = ModuleRenderer::new("nodejs")
+            .path(dir.path())
+            .config(toml::toml! {
+                [nodejs]
+                format = "via [$symbol($version )($engines_version )]($style)"
+            })
+            .collect();
+        let expected = Some(format!("via {}", Color::Green.bold().paint(" v12.0.0 ")));
+
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
     #[test]
     fn no_node_installed() -> io::Result<()> {
         let dir = tempfile::tempdir()?;