Support other variables than PATH in pathvar (#3791)

* Fix swapped PATH env var separators

* Support pathvar to manipulate other vars than PATH

* Add tests for pathvar and its subcommands

* Fix PATH env name for Windows

Seems like Windows uses PATH as well.

Co-authored-by: Jakub Žádník <jakub.zadnik@tuni.fi>

crates/nu-command/src/commands/pathvar/add.rs

@@ -1,9 +1,10 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
 use nu_protocol::{Signature, SyntaxShape};
 use nu_source::Tagged;
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 use std::path::PathBuf;
 
 pub struct SubCommand;
@@ -14,7 +15,14 @@ impl WholeStreamCommand for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar add").required("path", SyntaxShape::FilePath, "path to add")
+        Signature::build("pathvar add")
+            .required("path", SyntaxShape::FilePath, "path to add")
+            .named(
+                "var",
+                SyntaxShape::String,
+                "Use a different variable than PATH",
+                Some('v'),
+            )
     }
 
     fn usage(&self) -> &str {
@@ -37,17 +45,21 @@ impl WholeStreamCommand for SubCommand {
 pub fn add(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let ctx = &args.context;
 
+    let var = get_var(&args)?;
     let path_to_add: Tagged<PathBuf> = args.req(0)?;
     let path = path_to_add.item.into_os_string().into_string();
 
     if let Ok(mut path) = path {
         path.push(NATIVE_PATH_ENV_SEPARATOR);
-        if let Some(old_pathvar) = ctx.scope.get_env(NATIVE_PATH_ENV_VAR) {
+        if let Some(old_pathvar) = ctx.scope.get_env(&var) {
             path.push_str(&old_pathvar);
-            ctx.scope.add_env_var(NATIVE_PATH_ENV_VAR, path);
+            ctx.scope.add_env_var(&var.item, path);
             Ok(OutputStream::empty())
         } else {
-            Err(ShellError::unexpected("PATH not set"))
+            Err(ShellError::unexpected(&format!(
+                "Variable {} not set",
+                &var.item
+            )))
         }
     } else {
         Err(ShellError::labeled_error(

crates/nu-command/src/commands/pathvar/append.rs

@@ -1,9 +1,10 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
 use nu_protocol::{Signature, SyntaxShape};
 use nu_source::Tagged;
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 use std::path::PathBuf;
 
 pub struct SubCommand;
@@ -14,7 +15,14 @@ impl WholeStreamCommand for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar append").required("path", SyntaxShape::FilePath, "path to append")
+        Signature::build("pathvar append")
+            .required("path", SyntaxShape::FilePath, "path to append")
+            .named(
+                "var",
+                SyntaxShape::String,
+                "Use a different variable than PATH",
+                Some('v'),
+            )
     }
 
     fn usage(&self) -> &str {
@@ -36,17 +44,22 @@ impl WholeStreamCommand for SubCommand {
 
 pub fn add(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let ctx = &args.context;
+
+    let var = get_var(&args)?;
     let path_to_append_arg: Tagged<PathBuf> = args.req(0)?;
     let path_to_append = path_to_append_arg.item.into_os_string().into_string();
 
     if let Ok(path) = path_to_append {
-        if let Some(mut pathvar) = ctx.scope.get_env(NATIVE_PATH_ENV_VAR) {
+        if let Some(mut pathvar) = ctx.scope.get_env(&var) {
             pathvar.push(NATIVE_PATH_ENV_SEPARATOR);
             pathvar.push_str(&path);
-            ctx.scope.add_env_var(NATIVE_PATH_ENV_VAR, pathvar);
+            ctx.scope.add_env_var(&var.item, pathvar);
             Ok(OutputStream::empty())
         } else {
-            Err(ShellError::unexpected("PATH not set"))
+            Err(ShellError::unexpected(&format!(
+                "Variable {} not set",
+                &var.item
+            )))
         }
     } else {
         Err(ShellError::labeled_error(

crates/nu-command/src/commands/pathvar/command.rs

@@ -1,8 +1,9 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, Value};
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_protocol::{Signature, SyntaxShape, Value};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 
 pub struct Command;
 
@@ -12,11 +13,17 @@ impl WholeStreamCommand for Command {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar")
+        Signature::build("pathvar").named(
+            "var",
+            SyntaxShape::String,
+            "Use a different variable than PATH",
+            Some('v'),
+        )
     }
 
     fn usage(&self) -> &str {
-        "Manipulate the PATH variable (or pathvar)."
+        r#"Manipulate the PATH variable (pathvar) or a different variable following the
+same rules."#
     }
 
     fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
@@ -30,6 +37,11 @@ impl WholeStreamCommand for Command {
                 example: "pathvar",
                 result: None,
             },
+            Example {
+                description: "Display the current session's LD_LIBRARY_PATH",
+                example: "pathvar -v LD_LIBRARY_PATH",
+                result: None,
+            },
             Example {
                 description: "Add /usr/bin to the pathvar",
                 example: "pathvar add /usr/bin",
@@ -45,7 +57,9 @@ impl WholeStreamCommand for Command {
 }
 
 pub fn get_pathvar(args: CommandArgs) -> Result<OutputStream, ShellError> {
-    if let Some(pathvar) = args.context.scope.get_env(NATIVE_PATH_ENV_VAR) {
+    let var = get_var(&args)?;
+
+    if let Some(pathvar) = args.context.scope.get_env(&var) {
         let pathvar: Vec<Value> = pathvar
             .split(NATIVE_PATH_ENV_SEPARATOR)
             .map(Value::from)
@@ -53,6 +67,9 @@ pub fn get_pathvar(args: CommandArgs) -> Result<OutputStream, ShellError> {
 
         Ok(OutputStream::from(pathvar))
     } else {
-        Err(ShellError::unexpected("PATH not set"))
+        Err(ShellError::unexpected(&format!(
+            "Variable {} not set",
+            &var.item
+        )))
     }
 }

crates/nu-command/src/commands/pathvar/mod.rs

@@ -11,3 +11,15 @@ pub use command::Command as Pathvar;
 pub use remove::SubCommand as PathvarRemove;
 pub use reset::SubCommand as PathvarReset;
 pub use save::SubCommand as PathvarSave;
+
+use nu_engine::CommandArgs;
+use nu_errors::ShellError;
+use nu_source::{Tagged, TaggedItem};
+use nu_test_support::NATIVE_PATH_ENV_VAR;
+
+fn get_var(args: &CommandArgs) -> Result<Tagged<String>, ShellError> {
+    Ok(args
+        .get_flag("var")?
+        .unwrap_or_else(|| String::from(NATIVE_PATH_ENV_VAR))
+        .tagged_unknown())
+}

crates/nu-command/src/commands/pathvar/remove.rs

@@ -1,9 +1,10 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
 use nu_protocol::{Signature, SyntaxShape};
 use nu_source::Tagged;
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 
 pub struct SubCommand;
 
@@ -13,11 +14,18 @@ impl WholeStreamCommand for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar remove").required(
-            "index",
-            SyntaxShape::Int,
-            "index of the path to remove (starting at 0)",
-        )
+        Signature::build("pathvar remove")
+            .required(
+                "index",
+                SyntaxShape::Int,
+                "index of the path to remove (starting at 0)",
+            )
+            .named(
+                "var",
+                SyntaxShape::String,
+                "Use a different variable than PATH",
+                Some('v'),
+            )
     }
 
     fn usage(&self) -> &str {
@@ -39,10 +47,12 @@ impl WholeStreamCommand for SubCommand {
 
 pub fn remove(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let ctx = &args.context;
+
+    let var = get_var(&args)?;
     let index_to_remove_arg: Tagged<u64> = args.req(0)?;
     let index_to_remove = index_to_remove_arg.item as usize;
 
-    if let Some(old_pathvar) = ctx.scope.get_env(NATIVE_PATH_ENV_VAR) {
+    if let Some(old_pathvar) = ctx.scope.get_env(&var) {
         let mut paths: Vec<&str> = old_pathvar.split(NATIVE_PATH_ENV_SEPARATOR).collect();
 
         if index_to_remove >= paths.len() {
@@ -55,12 +65,15 @@ pub fn remove(args: CommandArgs) -> Result<OutputStream, ShellError> {
 
         paths.remove(index_to_remove);
         ctx.scope.add_env_var(
-            NATIVE_PATH_ENV_VAR,
+            &var.item,
             paths.join(&NATIVE_PATH_ENV_SEPARATOR.to_string()),
         );
 
         Ok(OutputStream::empty())
     } else {
-        Err(ShellError::unexpected("PATH not set"))
+        Err(ShellError::unexpected(&format!(
+            "Variable {} not set",
+            &var.item
+        )))
     }
 }

crates/nu-command/src/commands/pathvar/reset.rs

@@ -1,8 +1,9 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, UntaggedValue};
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 
 pub struct SubCommand;
 
@@ -12,7 +13,12 @@ impl WholeStreamCommand for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar reset")
+        Signature::build("pathvar reset").named(
+            "var",
+            SyntaxShape::String,
+            "Use a different variable than PATH",
+            Some('v'),
+        )
     }
 
     fn usage(&self) -> &str {
@@ -23,24 +29,29 @@ impl WholeStreamCommand for SubCommand {
         reset(args)
     }
 }
+
 pub fn reset(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let name = args.call_info.name_tag.clone();
     let ctx = &args.context;
 
+    let var = get_var(&args)?;
+    let var_lower = var.clone().map(|s| s.to_lowercase());
+
     if let Some(global_cfg) = &mut ctx.configs().lock().global_config {
-        let default_pathvar = global_cfg.vars.get("path");
+        let default_pathvar = global_cfg.vars.get(&var_lower.item);
         if let Some(pathvar) = default_pathvar {
             if let UntaggedValue::Table(paths) = &pathvar.value {
                 let pathvar_str = paths
                     .iter()
                     .map(|x| x.as_string().expect("Error converting path to string"))
                     .join(&NATIVE_PATH_ENV_SEPARATOR.to_string());
-                ctx.scope.add_env_var(NATIVE_PATH_ENV_VAR, pathvar_str);
+                ctx.scope.add_env_var(&var.item, pathvar_str);
             }
         } else {
-            return Err(ShellError::untagged_runtime_error(
-                "Default path is not set in config file.",
-            ));
+            return Err(ShellError::untagged_runtime_error(&format!(
+                "Default {} is not set in config file.",
+                &var_lower.item
+            )));
         }
         Ok(OutputStream::empty())
     } else {

crates/nu-command/src/commands/pathvar/save.rs

@@ -1,8 +1,9 @@
+use super::get_var;
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, UntaggedValue, Value};
-use nu_test_support::{NATIVE_PATH_ENV_SEPARATOR, NATIVE_PATH_ENV_VAR};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue, Value};
+use nu_test_support::NATIVE_PATH_ENV_SEPARATOR;
 
 pub struct SubCommand;
 
@@ -12,7 +13,12 @@ impl WholeStreamCommand for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("pathvar save")
+        Signature::build("pathvar save").named(
+            "var",
+            SyntaxShape::String,
+            "Use a different variable than PATH",
+            Some('v'),
+        )
     }
 
     fn usage(&self) -> &str {
@@ -27,8 +33,11 @@ pub fn save(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let name = args.call_info.name_tag.clone();
     let ctx = &args.context;
 
+    let var = get_var(&args)?;
+    let var_lower = var.clone().map(|s| s.to_lowercase());
+
     if let Some(global_cfg) = &mut ctx.configs().lock().global_config {
-        if let Some(pathvar) = ctx.scope.get_env(NATIVE_PATH_ENV_VAR) {
+        if let Some(pathvar) = ctx.scope.get_env(&var) {
             let paths: Vec<Value> = pathvar
                 .split(NATIVE_PATH_ENV_SEPARATOR)
                 .map(Value::from)
@@ -40,13 +49,16 @@ pub fn save(args: CommandArgs) -> Result<OutputStream, ShellError> {
                 Tag::from(Span::from(&span_range)),
             );
 
-            global_cfg.vars.insert("path".to_string(), row);
+            global_cfg.vars.insert(var_lower.item, row);
             global_cfg.write()?;
             ctx.reload_config(global_cfg)?;
 
             Ok(OutputStream::empty())
         } else {
-            Err(ShellError::unexpected("PATH not set"))
+            Err(ShellError::unexpected(&format!(
+                "Variable {} not set",
+                &var.item
+            )))
         }
     } else {
         let value = UntaggedValue::Error(crate::commands::config::err_no_global_cfg_present())

crates/nu-command/tests/commands/mod.rs

@@ -37,6 +37,7 @@ mod move_;
 mod open;
 mod parse;
 mod path;
+mod pathvar;
 mod prepend;
 mod random;
 mod range;

crates/nu-command/tests/commands/pathvar/mod.rs

@@ -0,0 +1,372 @@
+use nu_test_support::fs::Stub::FileWithContent;
+use nu_test_support::fs::{AbsolutePath, DisplayPath};
+use nu_test_support::playground::{says, Playground};
+use nu_test_support::{nu, NATIVE_PATH_ENV_SEPARATOR};
+
+use std::path::PathBuf;
+
+use hamcrest2::assert_that;
+use hamcrest2::prelude::*;
+
+/// Helper function that joins string literals with ':' or ';', based on host OS
+fn join_env_sep(pieces: &[&str]) -> String {
+    let sep_string = String::from(NATIVE_PATH_ENV_SEPARATOR);
+    pieces.join(&sep_string)
+}
+
+// Helpers
+
+#[cfg(windows)]
+#[test]
+fn joins_env_on_windows() {
+    let pieces = ["sausage", "bacon", "spam"];
+    let actual = join_env_sep(&pieces);
+
+    assert_eq!(&actual, "sausage;bacon;spam");
+}
+
+#[cfg(not(windows))]
+#[test]
+fn joins_env_on_non_windows() {
+    let pieces = ["sausage", "bacon", "spam"];
+    let actual = join_env_sep(&pieces);
+
+    assert_eq!(&actual, "sausage:bacon:spam");
+}
+
+// pathvar
+
+#[test]
+fn pathvar_correctly_reads_path_from_config_and_env() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+
+                path = ["/Users/andresrobalino/.volta/bin", "/Users/mosqueteros/bin"]
+                "#,
+            )])
+            .with_config(&file)
+            .with_env(
+                nu_test_support::NATIVE_PATH_ENV_VAR,
+                &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+            );
+
+        let expected =
+            "/Users/andresrobalino/.volta/bin-/Users/mosqueteros/bin-/Users/mosquito/proboscis";
+        let actual = sandbox.pipeline(r#" pathvar | str collect '-' "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_correctly_reads_env_var_from_config_and_env() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env(
+            "BREAKFAST",
+            &join_env_sep(&["egg", "sausage", "bacon", "spam"]),
+        );
+
+        let expected = "egg-sausage-bacon-spam";
+        let actual = sandbox.pipeline(r#" pathvar -v BREAKFAST | str collect '-' "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// pathvar add
+
+#[test]
+fn pathvar_adds_to_path() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env(
+            nu_test_support::NATIVE_PATH_ENV_VAR,
+            &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+        );
+
+        let expected = "spam-/Users/mosquito/proboscis";
+        let actual = sandbox.pipeline(r#" pathvar add spam; $nu.path | str collect '-' "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_adds_to_env_var() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env("BREAKFAST", &join_env_sep(&["egg", "sausage", "bacon"]));
+
+        let expected = join_env_sep(&["spam", "egg", "sausage", "bacon"]);
+        let actual = sandbox.pipeline(r#" pathvar add -v BREAKFAST spam; $nu.env.BREAKFAST "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// pathvar append
+
+#[test]
+fn pathvar_appends_to_path() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env(
+            nu_test_support::NATIVE_PATH_ENV_VAR,
+            &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+        );
+
+        let expected = "/Users/mosquito/proboscis-spam";
+        let actual = sandbox.pipeline(r#" pathvar append spam; $nu.path | str collect '-' "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_appends_to_env_var() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env("BREAKFAST", &join_env_sep(&["egg", "sausage", "bacon"]));
+
+        let expected = join_env_sep(&["egg", "sausage", "bacon", "spam"]);
+        let actual = sandbox.pipeline(r#" pathvar append -v BREAKFAST spam; $nu.env.BREAKFAST "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// pathvar remove
+
+#[test]
+fn pathvar_removes_from_path() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env(
+            nu_test_support::NATIVE_PATH_ENV_VAR,
+            &join_env_sep(&["/Users/mosquito/proboscis", "spam"]),
+        );
+
+        let expected = "/Users/mosquito/proboscis";
+        let actual = sandbox.pipeline(r#" pathvar remove 1; $nu.path"#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_removes_from_env_var() {
+    Playground::setup("hi_there", |_, sandbox| {
+        sandbox.with_env(
+            "BREAKFAST",
+            &join_env_sep(&["egg", "sausage", "bacon", "spam"]),
+        );
+
+        let expected = join_env_sep(&["egg", "sausage", "bacon"]);
+        let actual = sandbox.pipeline(r#" pathvar remove -v BREAKFAST 3; $nu.env.BREAKFAST "#);
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// pathvar reset
+
+#[test]
+fn pathvar_resets_path_from_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+
+                path = ["/Users/andresrobalino/.volta/bin", "/Users/mosqueteros/bin"]
+                "#,
+            )])
+            .with_config(&file)
+            .with_env(
+                nu_test_support::NATIVE_PATH_ENV_VAR,
+                &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+            );
+
+        let expected = "/Users/andresrobalino/.volta/bin-/Users/mosqueteros/bin";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar reset
+                pathvar | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_resets_env_var_from_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+
+                breakfast = ["egg", "sausage", "bacon"]
+                "#,
+            )])
+            .with_config(&file)
+            .with_env(
+                "BREAKFAST",
+                &join_env_sep(&["egg", "sausage", "bacon", "spam"]),
+            );
+
+        let expected = "egg-sausage-bacon";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar reset -v BREAKFAST
+                pathvar -v BREAKFAST | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// pathvar save
+
+#[test]
+fn pathvar_saves_path_to_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+
+                path = ["/Users/andresrobalino/.volta/bin", "/Users/mosqueteros/bin"]
+                "#,
+            )])
+            .with_config(&file)
+            .with_env(
+                nu_test_support::NATIVE_PATH_ENV_VAR,
+                &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+            );
+
+        let expected =
+            "/Users/andresrobalino/.volta/bin-/Users/mosqueteros/bin-/Users/mosquito/proboscis";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar save
+                $nu.path | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_saves_env_var_to_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+
+                breakfast = ["egg", "sausage", "bacon"]
+                "#,
+            )])
+            .with_config(&file)
+            .with_env("BREAKFAST", "spam");
+
+        let expected = "spam";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar save -v BREAKFAST
+                (config).breakfast | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_saves_new_path_to_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+                "#,
+            )])
+            .with_config(&file)
+            .with_env(
+                nu_test_support::NATIVE_PATH_ENV_VAR,
+                &PathBuf::from("/Users/mosquito/proboscis").display_path(),
+            );
+
+        let expected = "/Users/mosquito/proboscis";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar save
+                $nu.path | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+#[test]
+fn pathvar_saves_new_env_var_to_config() {
+    Playground::setup("hi_there", |dirs, sandbox| {
+        let file = AbsolutePath::new(dirs.test().join("config.toml"));
+
+        sandbox
+            .with_files(vec![FileWithContent(
+                "config.toml",
+                r#"
+                skip_welcome_message = true
+                "#,
+            )])
+            .with_config(&file)
+            .with_env("BREAKFAST", "spam");
+
+        let expected = "spam";
+        let actual = sandbox.pipeline(
+            r#"
+                pathvar save -v BREAKFAST
+                (config).breakfast | str collect '-'
+            "#,
+        );
+
+        assert_that!(actual, says().stdout(&expected));
+    })
+}
+
+// test some errors
+
+#[test]
+fn pathvar_error_non_existent_env_var() {
+    Playground::setup("hi_there", |dirs, _| {
+        let actual = nu!(
+            cwd: dirs.test(),
+            "pathvar -v EGGS_BACON_SPAM_SAUSAGE_SPAM_AND_SPAM_WITH_EXTRA_SPAM"
+        );
+
+        assert!(actual.err.contains("Error"));
+        assert!(actual.err.contains("not set"));
+    })
+}

crates/nu-test-support/src/lib.rs

@@ -9,15 +9,12 @@ pub struct Outcome {
     pub err: String,
 }
 
-#[cfg(windows)]
-pub const NATIVE_PATH_ENV_VAR: &str = "Path";
-#[cfg(not(windows))]
 pub const NATIVE_PATH_ENV_VAR: &str = "PATH";
 
 #[cfg(windows)]
-pub const NATIVE_PATH_ENV_SEPARATOR: char = ':';
-#[cfg(not(windows))]
 pub const NATIVE_PATH_ENV_SEPARATOR: char = ';';
+#[cfg(not(windows))]
+pub const NATIVE_PATH_ENV_SEPARATOR: char = ':';
 
 impl Outcome {
     pub fn new(out: String, err: String) -> Outcome {