feat(scripts): per-cycle ruby uninstall via RUBY_VERSION

scripts/install_ruby.sh

@@ -5,6 +5,9 @@
 . "$DIR/lib/common.sh"
 
 ACTION="${1:-reconcile}"
+# Remember whether the caller pinned a version — uninstall treats an explicit
+# RUBY_VERSION as "remove only this cycle" (like NODE_VERSION/UV_PYTHON_SPEC)
+RUBY_VERSION_EXPLICIT="${RUBY_VERSION:+1}"
 # Target Ruby version (default: latest stable)
 RUBY_VERSION="${RUBY_VERSION:-3.3.6}"
 
@@ -79,8 +82,10 @@
   fi
 
   # Check version before install
-  local before="$(get_specific_ruby_version "$RUBY_VERSION")"
-  local version_cycle="$(get_version_cycle "$RUBY_VERSION")"
+  local before
+  before="$(get_specific_ruby_version "$RUBY_VERSION")"
+  local version_cycle
+  version_cycle="$(get_version_cycle "$RUBY_VERSION")"
   local display_name="ruby"
   [ -n "$version_cycle" ] && display_name="ruby@${version_cycle}"
 
@@ -99,7 +104,8 @@
   fi
 
   # Only set global if no global version is set yet
-  local current_global="$(rbenv global 2>/dev/null || true)"
+  local current_global
+  current_global="$(rbenv global 2>/dev/null || true)"
   if [ -z "$current_global" ] || [ "$current_global" = "system" ]; then
     rbenv global "$RUBY_VERSION" || true
   fi
@@ -113,7 +119,8 @@
   rbenv rehash || true
 
   # Report version for this specific install
-  local after="$(get_specific_ruby_version "$RUBY_VERSION")"
+  local after
+  after="$(get_specific_ruby_version "$RUBY_VERSION")"
   local path="$HOME/.rbenv/versions/$RUBY_VERSION/bin/ruby"
   printf "[%s] before: %s\n" "$display_name" "${before:-<none>}"
   printf "[%s] after:  %s\n" "$display_name" "${after:-<none>}"
@@ -133,7 +140,42 @@
 }
 
 uninstall_ruby() {
-  # Remove rbenv-managed Ruby
+  if [ -n "$RUBY_VERSION_EXPLICIT" ]; then
+    # Multi-version: only remove the requested cycle, keep rbenv and other versions
+    if ! have rbenv && [ -x "$HOME/.rbenv/bin/rbenv" ]; then
+      export PATH="$HOME/.rbenv/bin:$PATH"
+    fi
+    if ! have rbenv; then
+      echo "[ruby] rbenv not found; nothing to remove for cycle $RUBY_VERSION" >&2
+      return 0
+    fi
+
+    local cycle cycle_re resolved
+    cycle="$(get_version_cycle "$RUBY_VERSION")"
+    cycle_re="^${cycle//./\\.}(\\.|$)"
+    resolved="$(rbenv versions --bare 2>/dev/null | grep -E "$cycle_re" || true)"
+    if [ -z "$resolved" ]; then
+      echo "[ruby] Ruby $RUBY_VERSION not found in rbenv" >&2
+      return 0
+    fi
+
+    local current_global other_ver v
+    current_global="$(rbenv global 2>/dev/null || true)"
+    for v in $resolved; do
+      if [ "$v" = "$current_global" ]; then
+        other_ver="$(rbenv versions --bare 2>/dev/null | grep -vE "$cycle_re" | tail -1 || true)"
+        if [ -n "$other_ver" ]; then
+          echo "[ruby] Warning: ruby $v is the current global, switching to $other_ver first" >&2
+          rbenv global "$other_ver" || true
+        fi
+      fi
+      rbenv uninstall -f "$v" || true
+      echo "[ruby] Removed ruby $v (cycle $cycle)" >&2
+    done
+    return 0
+  fi
+
+  # Full uninstall: remove rbenv-managed Ruby entirely
   if [ -d "$HOME/.rbenv" ]; then
     rm -rf "$HOME/.rbenv"
   fi

tests/test_ruby_uninstall.py

@@ -0,0 +1,136 @@
+"""Tests for per-cycle ruby uninstall (RUBY_VERSION=3.3 install_ruby.sh uninstall).
+
+node (NODE_VERSION) and python (UV_PYTHON_SPEC) support removing a single
+version cycle; ruby's uninstall previously always nuked all of ~/.rbenv.
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+skip_on_windows = pytest.mark.skipif(
+    sys.platform == "win32", reason="Shell script tests require POSIX shell"
+)
+
+SCRIPT = Path(__file__).parent.parent / "scripts" / "install_ruby.sh"
+
+RBENV_STUB = """#!/usr/bin/env bash
+echo "rbenv $*" >> "$RBENV_STUB_LOG"
+case "$1" in
+  versions)
+    printf '%s\\n' $RBENV_STUB_VERSIONS
+    ;;
+  global)
+    if [ $# -eq 1 ]; then echo "$RBENV_STUB_GLOBAL"; fi
+    ;;
+esac
+exit 0
+"""
+
+
+@skip_on_windows
+class TestRubyPerCycleUninstall:
+    def _run(self, tmpdir: str, env_extra: dict, versions: str, global_ver: str,
+             args: list[str]) -> tuple[subprocess.CompletedProcess, str, Path]:
+        stub_dir = Path(tmpdir) / "stubs"
+        stub_dir.mkdir(exist_ok=True)
+        log = Path(tmpdir) / "rbenv.log"
+        log.touch()
+        for name, body in (
+            ("rbenv", RBENV_STUB),
+            # keep the full-uninstall branch harmless if ever reached
+            ("sudo", "#!/usr/bin/env bash\nexit 0\n"),
+            ("dpkg", "#!/usr/bin/env bash\nexit 1\n"),
+            ("apt-get", "#!/usr/bin/env bash\nexit 0\n"),
+        ):
+            stub = stub_dir / name
+            stub.write_text(body)
+            stub.chmod(0o755)
+
+        home = Path(tmpdir) / "home"
+        (home / ".rbenv" / "versions").mkdir(parents=True, exist_ok=True)
+
+        env = {
+            **os.environ,
+            "HOME": str(home),
+            "PATH": f"{stub_dir}:{os.environ['PATH']}",
+            "RBENV_STUB_LOG": str(log),
+            "RBENV_STUB_VERSIONS": versions,
+            "RBENV_STUB_GLOBAL": global_ver,
+            **env_extra,
+        }
+        env.pop("RUBY_VERSION", None)
+        env.update({k: v for k, v in env_extra.items()})
+        result = subprocess.run(
+            ["bash", str(SCRIPT), *args],
+            capture_output=True, text=True, timeout=30, env=env,
+        )
+        return result, log.read_text(), home
+
+    def test_removes_only_requested_cycle(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result, log, home = self._run(
+                tmpdir, {"RUBY_VERSION": "3.3"},
+                versions="3.3.6 4.0.1 4.0.5", global_ver="4.0.5",
+                args=["uninstall"],
+            )
+            assert result.returncode == 0, result.stderr
+            assert "rbenv uninstall -f 3.3.6" in log
+            assert "uninstall -f 4.0.1" not in log
+            assert "uninstall -f 4.0.5" not in log
+            # rbenv itself must survive a per-cycle removal
+            assert (home / ".rbenv").exists()
+
+    def test_full_version_spec_removes_its_cycle(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result, log, _ = self._run(
+                tmpdir, {"RUBY_VERSION": "3.3.6"},
+                versions="3.3.6 4.0.5", global_ver="4.0.5",
+                args=["uninstall"],
+            )
+            assert result.returncode == 0, result.stderr
+            assert "rbenv uninstall -f 3.3.6" in log
+
+    def test_switches_global_before_removing_it(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result, log, _ = self._run(
+                tmpdir, {"RUBY_VERSION": "3.3"},
+                versions="3.3.6 4.0.5", global_ver="3.3.6",
+                args=["uninstall"],
+            )
+            assert result.returncode == 0, result.stderr
+            lines = [line for line in log.splitlines() if line]
+            assert "rbenv global 4.0.5" in lines
+            assert lines.index("rbenv global 4.0.5") < lines.index(
+                "rbenv uninstall -f 3.3.6"
+            )
+
+    def test_missing_cycle_is_a_noop(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result, log, home = self._run(
+                tmpdir, {"RUBY_VERSION": "3.1"},
+                versions="3.3.6 4.0.5", global_ver="4.0.5",
+                args=["uninstall"],
+            )
+            assert result.returncode == 0, result.stderr
+            assert "uninstall -f" not in log
+            assert "not found" in result.stderr + result.stdout
+            assert (home / ".rbenv").exists()
+
+    def test_full_uninstall_without_ruby_version_still_removes_rbenv(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            result, _, home = self._run(
+                tmpdir, {},
+                versions="3.3.6 4.0.5", global_ver="4.0.5",
+                args=["uninstall"],
+            )
+            assert result.returncode == 0, result.stderr
+            assert not (home / ".rbenv").exists(), (
+                "full uninstall must keep removing ~/.rbenv entirely"
+            )