exits as error if the virtual environment doesn't have python executable (#104)

conda's environment might not have `python` executable. If the prefix
doesn't contain `python` in it, `pyenv-which` might be ran into infinite
loop if some of `which` hooks invoke `pyenv-virtualenv-prefix`.

Author: yyuu

bin/pyenv-virtualenv-prefix

@@ -37,11 +37,16 @@ for version in "${versions[@]}"; do
     exit 1
   fi
   PYENV_PREFIX_PATH="$(pyenv-prefix "${version}")"
-  if [ -f "${PYENV_PREFIX_PATH}/bin/activate" ]; then
-    VIRTUALENV_PREFIX_PATH="$(real_prefix "${version}" || base_prefix "${version}" || true)"
-    VIRTUALENV_PREFIX_PATHS=("${VIRTUALENV_PREFIX_PATHS[@]}" "${VIRTUALENV_PREFIX_PATH:-${PYENV_PREFIX_PATH}}")
+  if [ -x "${PYENV_PREFIX_PATH}/bin/python" ]; then
+    if [ -f "${PYENV_PREFIX_PATH}/bin/activate" ]; then
+      VIRTUALENV_PREFIX_PATH="$(real_prefix "${version}" || base_prefix "${version}" || true)"
+      VIRTUALENV_PREFIX_PATHS=("${VIRTUALENV_PREFIX_PATHS[@]}" "${VIRTUALENV_PREFIX_PATH:-${PYENV_PREFIX_PATH}}")
+    else
+      echo "pyenv-virtualenv: version \`${version}' is not a virtualenv" 1>&2
+      exit 1
+    fi
   else
-    echo "pyenv-virtualenv: version \`${version}' is not a virtualenv" 1>&2
+    echo "pyenv-virtualenv: \`python' not found in version \`${version}'" 1>&2
     exit 1
   fi
 done

test/prefix.bats

@@ -6,13 +6,23 @@ setup() {
   export PYENV_ROOT="${TMP}/pyenv"
 }
 
-create_virtualenv() {
+create_version() {
   mkdir -p "${PYENV_ROOT}/versions/$1/bin"
+  touch "${PYENV_ROOT}/versions/$1/bin/python"
+  chmod +x "${PYENV_ROOT}/versions/$1/bin/python"
+}
+
+remove_version() {
+  rm -fr "${PYENV_ROOT}/versions/$1"
+}
+
+create_virtualenv() {
+  create_version "$@"
   touch "${PYENV_ROOT}/versions/$1/bin/activate"
 }
 
 remove_virtualenv() {
-  rm -fr "${PYENV_ROOT}/versions/$1"
+  remove_version "$@"
 }
 
 @test "display prefix with using sys.real_prefix" {
@@ -118,13 +128,13 @@ OUT
 @test "should fail if the version is not a virtualenv" {
   stub pyenv-version-name "echo 3.4.0"
   stub pyenv-prefix "3.4.0 : echo \"${PYENV_ROOT}/versions/3.4.0\""
-  mkdir -p "${PYENV_ROOT}/versions/3.4.0"
+  create_version "3.4.0"
 
   PYENV_VERSION="3.4.0" run pyenv-virtualenv-prefix
 
   unstub pyenv-version-name
   unstub pyenv-prefix
-  rmdir "${PYENV_ROOT}/versions/3.4.0"
+  remove_version "3.4.0"
 
   assert_failure
   assert_output <<OUT
@@ -139,15 +149,15 @@ OUT
   stub pyenv-exec "false" \
                   "echo \"${PYENV_ROOT}/versions/3.3.3\""
   create_virtualenv "venv33"
-  mkdir -p "${PYENV_ROOT}/versions/3.4.0"
+  create_version "3.4.0"
 
   PYENV_VERSION="venv33:3.4.0" run pyenv-virtualenv-prefix
 
   unstub pyenv-version-name
   unstub pyenv-prefix
   unstub pyenv-exec
   remove_virtualenv "venv33"
-  rmdir "${PYENV_ROOT}/versions/3.4.0"
+  remove_version "3.4.0"
 
   assert_failure
   assert_output <<OUT

test/test_helper.bash

@@ -123,12 +123,16 @@ create_conda() {
   mkdir -p "${PYENV_ROOT}/versions/$version/bin"
   touch "${PYENV_ROOT}/versions/$version/bin/activate"
   touch "${PYENV_ROOT}/versions/$version/bin/conda"
+  touch "${PYENV_ROOT}/versions/$version/bin/python"
   chmod +x "${PYENV_ROOT}/versions/$version/bin/conda"
+  chmod +x "${PYENV_ROOT}/versions/$version/bin/python"
   local conda_env
   for conda_env; do
     mkdir -p "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin"
     touch "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin/activate"
     touch "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin/conda"
+    touch "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin/python"
     chmod +x "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin/conda"
+    chmod +x "${PYENV_ROOT}/versions/$version/envs/$conda_env/bin/python"
   done
 }