feat: add support for xonsh (#2807)

* feat: add support for xonsh

* xonsh: add STARSHIP_SESSION_KEY

* xonsh: implement STARSHIP_SESSION_KEY in xonsh

* docs: mention tcsh, elvish, and nu in more places

* xonsh: change STARSHIP_SESSION_KEY implementation

See https://github.com/starship/starship/pull/2807#discussion_r667064149

* xonsh: fix jobs implementation

* xonsh: do not silently discard stderr from starship

1 files changed, 31 insertions, 0 deletions

diff --git a/src/modules/shell.rs b/src/modules/shell.rs
index d8a5f8e0b..0b141ec8a 100644
--- a/src/modules/shell.rs
+++ b/src/modules/shell.rs
@@ -25,6 +25,7 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
                     Shell::Elvish => Some(config.elvish_indicator),
                     Shell::Tcsh => Some(config.tcsh_indicator),
                     Shell::Nu => Some(config.nu_indicator),
+                    Shell::Xonsh => Some(config.xonsh_indicator),
                     Shell::Unknown => Some(config.unknown_indicator),
                 },
                 _ => None,
@@ -37,6 +38,7 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
                 "ion_indicator" => Some(Ok(config.ion_indicator)),
                 "elvish_indicator" => Some(Ok(config.elvish_indicator)),
                 "tcsh_indicator" => Some(Ok(config.tcsh_indicator)),
+                "xonsh_indicator" => Some(Ok(config.xonsh_indicator)),
                 "unknown_indicator" => Some(Ok(config.unknown_indicator)),
                 _ => None,
             })
@@ -280,6 +282,35 @@ mod tests {
     }
 
     #[test]
+    fn test_xonsh_default_format() {
+        let expected = Some(format!("{} ", "xsh"));
+        let actual = ModuleRenderer::new("shell")
+            .shell(Shell::Xonsh)
+            .config(toml::toml! {
+                [shell]
+                disabled = false
+            })
+            .collect();
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn test_xonsh_custom_format() {
+        let expected = Some(format!("{} ", Color::Cyan.bold().paint("xonsh")));
+        let actual = ModuleRenderer::new("shell")
+            .shell(Shell::Xonsh)
+            .config(toml::toml! {
+                [shell]
+                xonsh_indicator = "[xonsh](bold cyan)"
+                disabled = false
+            })
+            .collect();
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
     fn test_custom_format_conditional_indicator_match() {
         let expected = Some(format!("{} ", "B"));
         let actual = ModuleRenderer::new("shell")