Add julia testing skill

scripts/julia-env-info

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+#!/usr/bin/env bash
+set -euo pipefail
+export LC_ALL=C
+
+have() { command -v "$1" >/dev/null 2>&1; }
+
+# -------- parse julia_version from Manifest.toml (BSD/GNU portable) --------
+read_manifest_version() {
+  awk -F= '
+    /^[[:space:]]*julia_version[[:space:]]*=/ {
+      v=$2
+      gsub(/^[[:space:]]+|[[:space:]]+$/, "", v)
+      gsub(/^"|"$/, "", v)
+      print v
+      exit
+    }
+  ' "$1" 2>/dev/null || true
+}
+
+# -------- parse juliaup api getconfig1 (no jq needed) --------
+read_juliaup_default() {
+  # Prints: "<channel_name>\t<version>\t<file>" OR nothing if unavailable
+  local cfg dc name ver file
+  cfg="$(juliaup api getconfig1 2>/dev/null || true)" || true
+  [ -z "${cfg:-}" ] && return 0
+  # Extract the DefaultChannel object
+  dc="$(printf '%s' "$cfg" | awk 'match($0,/"DefaultChannel"[[:space:]]*:[[:space:]]*\{[^}]*\}/){print substr($0,RSTART,RLENGTH)}')"
+  [ -z "${dc:-}" ] && return 0
+  # Pull fields (quoted strings)
+  name="$(printf '%s\n' "$dc" | grep -oE '"Name"[[:space:]]*:[[:space:]]*"[^"]*"'    | sed -E 's/.*"Name"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/'    || true)"
+  ver="$( printf '%s\n' "$dc" | grep -oE '"Version"[[:space:]]*:[[:space:]]*"[^"]*"' | sed -E 's/.*"Version"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/' || true)"
+  file="$(printf '%s\n' "$dc" | grep -oE '"File"[[:space:]]*:[[:space:]]*"[^"]*"'    | sed -E 's/.*"File"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/'    || true)"
+  [ -n "$name" ] && printf '%s\t%s\t%s\n' "$name" "$ver" "$file"
+}
+
+# ---------- ENV ----------
+ENV_TSV="$(mktemp)"; PROJ_TSV="$(mktemp)"; MAN_TSV="$(mktemp)"
+trap 'rm -f "$ENV_TSV" "$PROJ_TSV" "$MAN_TSV"' EXIT
+
+{
+  printf 'KEY\tVALUE\n'
+  jpath="$(command -v julia 2>/dev/null || true)"
+  julia_present="no"; julia_ver="unknown"
+  if [ -n "${jpath:-}" ]; then
+    julia_present="yes"
+    if "$jpath" -e 'print(VERSION)' >/dev/null 2>&1; then
+      julia_ver="$("$jpath" -e 'print(VERSION)' 2>/dev/null || printf 'unknown')"
+    fi
+  fi
+  printf 'julia_present\t%s\n' "$julia_present"
+  printf 'julia_path\t%s\n' "${jpath:-none}"
+  printf 'julia_version\t%s\n' "$julia_ver"
+
+  # juliaup details via API
+  juliaup_present="no"; uses_juliaup="no"; juliaup_default_channel="unknown"; juliaup_default_version="unknown"; juliaup_default_file="unknown"
+  if have juliaup; then
+    juliaup_present="yes"
+    case "${jpath:-}" in *".juliaup/"*) uses_juliaup="yes" ;; esac
+    if IFS=$'\t' read -r ch ver file < <(read_juliaup_default); then
+      juliaup_default_channel="$ch"
+      [ -n "${ver:-}" ] && juliaup_default_version="$ver"
+      [ -n "${file:-}" ] && juliaup_default_file="$file"
+    fi
+  fi
+  printf 'juliaup_present\t%s\n' "$juliaup_present"
+  printf 'uses_juliaup\t%s\n' "$uses_juliaup"
+  printf 'juliaup_default_channel\t%s\n' "$juliaup_default_channel"
+  printf 'juliaup_default_version\t%s\n' "$juliaup_default_version"
+  printf 'juliaup_default_file\t%s\n' "$juliaup_default_file"
+} >"$ENV_TSV"
+
+# ---------- PROJECTS ----------
+{
+  printf 'PATH\n'
+  find . -type f -name 'Project.toml' -print0 2>/dev/null \
+  | while IFS= read -r -d '' p; do printf '%s\n' "$p"; done
+} >"$PROJ_TSV"
+
+# ---------- MANIFESTS ----------
+{
+  printf 'PATH\tjulia_version\n'
+  find . -type f -name 'Manifest.toml' -print0 2>/dev/null \
+  | while IFS= read -r -d '' m; do
+      v="$(read_manifest_version "$m")"
+      printf '%s\t%s\n' "$m" "${v:-unknown}"
+    done
+} >"$MAN_TSV"
+
+# ---------- PRINT (pretty if `column` exists) ----------
+print_table() { if have column; then column -t -s $'\t' "$1"; else cat "$1"; fi; }
+
+printf 'ENV\n';       print_table "$ENV_TSV";  printf '\n'
+printf 'PROJECTS\n';  print_table "$PROJ_TSV"; printf '\n'
+printf 'MANIFESTS\n'; print_table "$MAN_TSV";  printf '\n'

skills/testing/julia-tests/SKILL.md

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+---
+name: Environments and tests in Julia
+description: How to correctly activate environments and run tests in Julia
+when_to_use: When running Julia tests, getting "LoadError" or package not found errors, seeing "Manifest out of date" warnings, struggling with --project flag, need to run specific test files, or want to add test-only dependencies. When working with Julia projects that have Project.toml/Manifest.toml files. When you need to find Julia documentation for functions or understand what test_args does.
+version: 2.1.0
+languages: julia
+---
+
+# Environments and Tests in Julia
+
+## Overview
+
+**Core principle:** Every Julia process needs `--project=DIR` to activate the correct environment. Tests need their own environment with test-specific dependencies.
+
+**Julia projects:** Each has a `Project.toml` (dependencies) and optionally `Manifest.toml` (lockfile).
+
+## Quick Reference
+
+| Task | Command |
+|------|---------|
+| Find all projects | `${SUPERPOWERS_SKILLS_ROOT}/scripts/julia-env-info` |
+| Get function documentation | `julia -e 'using Pkg; println(@doc Pkg.test)'` |
+| Run all tests | `julia --project=. -e 'using Pkg; Pkg.test()'` |
+| Run specific test file | `julia --project=. -e 'using TestEnv; TestEnv.activate(); include("test/file.jl")'` |
+| Fix "Manifest out of date" | `julia --project=. -e 'using Pkg; Pkg.resolve()'` |
+| Instantiate environment | `julia --project=. -e 'using Pkg; Pkg.instantiate()'` |
+| Add test-only dependency | `julia --project=test -e 'using Pkg; Pkg.add("Dep")'` OR `Pkg.add("Dep"; target=:extras)` |
+
+## Starting a Julia Task
+
+**1. Find all Julia projects in the repo:**
+```sh
+${SUPERPOWERS_SKILLS_ROOT}/scripts/julia-env-info
+```
+
+Shows:
+- Julia version
+- All Project.toml locations
+- All Manifest.toml files with their Julia versions
+
+**2. Activate the right project:**
+```sh
+julia --project=subdir -e '...'  # for subdir/Project.toml
+julia --project=. -e '...'       # for ./Project.toml
+```
+
+**Always use `--project` flag.** Without it, Julia uses the global environment.
+
+## Running Tests
+
+### Option 1: Run All Tests (Standard)
+
+```sh
+julia --project=. -e 'using Pkg; Pkg.test()'
+```
+
+**Use this when:**
+- Running full test suite
+- CI/CD
+- Not sure how tests are organized
+
+Pkg finds the test environment automatically.
+
+### Option 2: Run Specific Test Files
+
+**Requirements:**
+- TestEnv.jl installed globally: `julia -e 'using Pkg; Pkg.add("TestEnv")'`
+
+**Command:**
+```sh
+julia --project=. -e 'using TestEnv; TestEnv.activate(); include("test/mytests.jl")'
+```
+
+**Use this when:**
+- Full suite takes too long
+- Only changed specific code
+- Developing test-first
+
+### Option 3: Direct Test Environment Activation
+
+If `test/Project.toml` exists:
+```sh
+julia --project=test -e 'include("test/mytests.jl")'
+```
+
+Options 1 and 2 still work in this case.
+
+## Test-Only Dependencies
+
+Julia has two patterns:
+
+### Pattern 1: test/Project.toml
+
+**If `test/Project.toml` exists**, activate it:
+```sh
+julia --project=test -e 'using Pkg; Pkg.add("BenchmarkTools")'
+```
+
+### Pattern 2: [extras] in Main Project.toml
+
+**If main Project.toml has `[extras]` section:**
+
+**1. Add to [extras]:**
+```sh
+julia --project=. -e 'using Pkg; Pkg.add("BenchmarkTools"; target=:extras)'
+```
+
+**2. Manually update [targets]:**
+```toml
+[extras]
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
+
+[targets]
+test = ["Test", "BenchmarkTools"]  # Add BenchmarkTools here
+```
+
+**Which to use:** Check what exists. Don't mix both.
+
+## Common Issues
+
+### "Manifest out of date" Warning
+
+**Cause:** Project.toml changed (e.g., after `git pull`)
+
+**Fix:**
+```sh
+julia --project=. -e 'using Pkg; Pkg.resolve()'
+```
+
+### Version Mismatches
+
+**Cause:** Manifest.toml created with different Julia version
+
+**Check versions:**
+```sh
+${SUPERPOWERS_SKILLS_ROOT}/scripts/julia-env-info
+```
+
+Shows your Julia version and each Manifest's Julia version.
+
+**Fix:** Re-resolve manifest or delete it (ask user before deleting).
+
+### Tests Fail with LoadError
+
+**Cause:** Wrong environment activated or dependencies not installed
+
+**Fix:**
+1. Check `--project` flag points to correct directory
+2. Run `Pkg.instantiate()` to install dependencies
+3. For tests, use `Pkg.test()` not direct file execution
+
+## Common Mistakes
+
+| Mistake | Fix |
+|---------|-----|
+| `julia test/runtests.jl` | `julia --project=. test/runtests.jl` |
+| `Pkg.test(test_args=["file.jl"])` | `test_args` are command-line arguments (ARGS), NOT file selectors. Use TestEnv to run specific files. |
+| Deleting Manifest.toml carelessly | Ask user before deleting |
+| Missing `--project` flag | Add `--project=.` or `--project=DIR` |
+| Forgetting to resolve after pull | Run `Pkg.resolve()` |
+
+## Environment Types
+
+**Global:** Used without `--project`. Install dev tools here (TestEnv.jl).
+
+**Local:** Activated with `--project`. Package dependencies.
+
+**Stacked:** Local environment can use global packages, but packages can't declare undeclared global deps.