build: 🔨 add test of recopy and copy in existing project (#126)

# Description

This tests that copying also fixes deleted files or can be used in an
existing project.

Closes #122

This PR needs an in-depth review.

## Checklist

- [x] Ran `just run-all`

---------

Co-authored-by: martonvago <57952344+martonvago@users.noreply.github.com>

Author: lwjohnst86

justfile

@@ -32,12 +32,14 @@ check-spelling:
 # Test and check that a data package can be created from the template
 test:
   #!/bin/zsh
-  test_dir="$(pwd)/_temp"
   test_name="test-data-package"
+  test_dir="$(pwd)/_temp/$test_name"
+  template_dir="$(pwd)"
+  commit=$(git rev-parse HEAD)
   rm -rf $test_dir
   # vcs-ref means the current commit/head, not a tag.
-  # `.` means the current directory contains the template.
-  uvx copier copy --vcs-ref=HEAD . $test_dir/$test_name \
+  uvx copier copy $template_dir $test_dir \
+    --vcs-ref=$commit \
     --defaults \
     --trust \
     --data package_abbrev=$test_name \
@@ -48,7 +50,39 @@ test:
     --data review_team="@first-last/developers" \
     --data github_board_number=22
   # Run checks in the generated test data package
-  (cd $test_dir/$test_name && just check-python check-spelling)
+  cd $test_dir
+  git add .
+  git commit -m "test: initial copy"
+  just check-python check-spelling
+  # TODO: Find some way to test the `update` command
+  # Check that recopy works
+  echo "Testing recopy command -----------"
+  rm .cz.toml
+  git add .
+  git commit -m "test: preparing to recopy from the template"
+  uvx copier recopy \
+    --vcs-ref=$commit \
+    --defaults \
+    --overwrite \
+    --trust
+  # Check that copying onto an existing data package works
+  echo "Using the template in an existing package command -----------"
+  rm .cz.toml .copier-answers.yml LICENSE-MIT.md
+  git add .
+  git commit -m "test: preparing to copy onto an existing package"
+  uvx copier copy \
+    $template_dir $test_dir \
+    --vcs-ref=$commit \
+    --defaults \
+    --trust \
+    --overwrite \
+    --data package_abbrev=$test_name \
+    --data package_github_repo="first-last/${test_name}" \
+    --data author_given_name="First" \
+    --data author_family_name="Last" \
+    --data author_email="first.last@example.com" \
+    --data review_team="@first-last/developers" \
+    --data github_board_number=22
 
 # Clean up any leftover and temporary build files
 cleanup: