completions: Support options-only fish

Summary: Like it says in the title, wire this up. For now we return the options only completions even if the user doesn't ask for `--options-only`. That's ok, it's not wrong, it's just less feature-complete

Reviewed By: stepancheg

Differential Revision: D63085150

fbshipit-source-id: 3c65bfb1c759476f5025dc79fc74e9be80610800

app/buck2_client/src/commands/completion.rs

@@ -24,6 +24,7 @@ use clap_complete::generate;
 #[clap(rename_all = "kebab-case")]
 enum Shell {
     Bash,
+    Fish,
     Zsh,
 }
 
@@ -74,9 +75,10 @@ fn print_completion_script(
     let (wrapper, shell) = match shell_arg {
         Shell::Bash => (BASH_COMPLETION_WRAPPER, clap_complete::Shell::Bash),
         Shell::Zsh => (ZSH_COMPLETION_WRAPPER, clap_complete::Shell::Zsh),
+        Shell::Fish => ("", clap_complete::Shell::Fish),
     };
 
-    if options_only {
+    if options_only || shell == clap_complete::Shell::Fish {
         buck2_client_ctx::println!("{}", option_completions(shell, cmd)?)?;
         return Ok(());
     }

shed/completion_verify/packages/download.sh

@@ -12,3 +12,10 @@ dnf download "$1" --destdir "$BUCK_SCRATCH_PATH"
 rpm=$(echo "$BUCK_SCRATCH_PATH"/*)
 mkdir -p "$2"
 rpm2archive - < "$rpm" | tar -xvzf - -C "$(realpath "$2")"
+
+if [[ $1 =~ fish ]]; then
+    # In order to get fish to behave like it's been installed into a relocatable
+    # directory, we need to move things out of `usr/`
+    mv "$2/usr/"* "$2"
+    rmdir "$2/usr"
+fi

shed/completion_verify/src/main.rs

@@ -35,7 +35,7 @@ impl Shell {
             Self::Bash => Ok(Command::new("bash")),
             Self::Fish => {
                 let mut path = buck_resources::get("buck2/shed/completion_verify/fish").unwrap();
-                path.push("usr/bin/fish");
+                path.push("bin/fish");
                 Ok(Command::new(path))
             }
             Self::Zsh => {

tests/e2e/completion/test_completion.py

@@ -18,7 +18,8 @@
 
 IS_LINUX: bool = platform.system() == "Linux"
 
-SHELLS = ["bash", "zsh"]
+# Downloading fish on Mac is not straightforward, so only test it on Linux
+SHELLS = ["bash", "fish", "zsh"] if IS_LINUX else ["bash", "zsh"]
 
 
 def completion_test(
@@ -29,6 +30,9 @@ def completion_test(
     options_only: bool = False,
 ) -> None:
     for shell in shells:
+        if shell == "fish" and not options_only:
+            # Fish only supports options-only completions
+            continue
 
         # shell=shell is a trick to get the variable captured by value
         async def impl(buck: Buck, shell: str = shell) -> None:
@@ -81,8 +85,7 @@ async def impl(buck: Buck, shell: str = shell) -> None:
     # FIXME(JakobDegen): Should probably not be inconsistent
     expected=["test", "targets"] if IS_LINUX else ["targets", "test"],
     options_only=True,
-    # Skip this on zsh because it has fancy formatting with help messages for commands (and nothing
-    # else)
+    # Skip this on zsh and fish because they have fancy formatting with help messages for commands
     shells=["bash"],
 )
 

tests/e2e/help/test_help_data/buck2-help-completion.golden.txt

@@ -12,7 +12,7 @@ Arguments:
   <SHELL>
           shell for which to generate completion script
 
-          [possible values: bash, zsh]
+          [possible values: bash, fish, zsh]
 
 Options:
   -h, --help