pyenv-binary-package: refactor tests

* make them more human-readable
* don't double-test external code outside of integration tests

plugins/pyenv-binary/test/package.bats

@@ -24,17 +24,15 @@ stub_build_environment() {
   done
 }
 
-@test "completion lists the option and definitions provided by another plugin" {
-  mkdir -p "${PYENV_ROOT}/plugins/example/share/python-build"
-  touch "${PYENV_ROOT}/plugins/example/share/python-build/3.12.7-example"
-  PATH="${BATS_TEST_DIRNAME}/../../python-build/bin:${PATH}"
+@test "completions" {
+  create_stub pyenv-install 'echo "${0##*/} $*"'
 
   run pyenv-binary-package --complete
-  assert_success
-  assert_line "--archive-base-url"
-  assert_line "--verbose"
-  assert_line "3.12.7-example"
-  refute_line "Available versions:"
+  assert_success <<!
+--archive-base-url
+--verbose
+pyenv-install --list --bare
+!
 }
 
 @test "fails with no arguments" {
@@ -89,7 +87,7 @@ stub_build_environment() {
   assert_failure "pyenv-binary: macOS archives are not supported yet"
 }
 
-@test "writes the archive, metadata and definition under the entry name" {
+@test "writes the archive, metadata and definition under the entry name (integration)" {
   stub_build_environment
   cd "${BATS_TEST_TMPDIR}"
 
@@ -103,12 +101,24 @@ stub_build_environment() {
   assert_success "ARCHIVE_URL=http://example.com/binaries/3.12.7-test.tar.gz"
 }
 
-@test "strips a trailing slash from the archive base url" {
+@test "correctly joins archive base url with a trailing slash" {
   stub_build_environment
+  create_stub pyenv-binary-save true
+  create_stub pyenv-binary-generate-installer <<'!'
+echo -n "${0##*/} "
+while (($#)); do
+  case $1 in
+    --archive-url)
+      echo "$1 ${2:?}"
+      break
+      ;;
+  esac
+  shift
+done
+!
 
   run pyenv-binary-package 3.12.7:3.12.7-test \
     --archive-base-url http://example.com/binaries/
   assert_success
-  run grep '^ARCHIVE_URL=' "${BATS_TEST_TMPDIR}/3.12.7-test"
-  assert_success "ARCHIVE_URL=http://example.com/binaries/3.12.7-test.tar.gz"
+  assert_line "pyenv-binary-generate-installer --archive-url http://example.com/binaries/3.12.7-test.tar.gz"
 }