Auto-resolve prefixes to the latest version (#2487)

plugins/python-build/test/definitions.bats

@@ -60,11 +60,30 @@ NUM_DEFINITIONS="$(find "$BATS_TEST_DIRNAME"/../share/python-build -maxdepth 1 -
 }
 
 @test "installing nonexistent definition" {
+  stub pyenv-latest false
   run python-build "nonexistent" "${TMP}/install"
   assert [ "$status" -eq 2 ]
   assert_output "python-build: definition not found: nonexistent"
 }
 
+@test "resolves prefixes via pyenv-latest" {
+  stub pyenv-latest "echo 2.7.8"
+  export PYTHON_BUILD_ROOT="$TMP"
+  mkdir -p "${PYTHON_BUILD_ROOT}/share/python-build"
+  echo 'echo 2.7.8' > "${PYTHON_BUILD_ROOT}/share/python-build/2.7.8"
+  run python-build "2.7" "${TMP}/install"
+  assert_success "2.7.8"
+}
+
+@test "doesn't resolve prefixes if pyenv-latest is unavailable" {
+  export PATH="$(path_without pyenv-latest)"
+  export PYTHON_BUILD_ROOT="$TMP"
+  mkdir -p "${PYTHON_BUILD_ROOT}/share/python-build"
+  echo 'echo 2.7.8' > "${PYTHON_BUILD_ROOT}/share/python-build/2.7.8"
+  run python-build "2.7" "${TMP}/install"
+  assert_failure "python-build: definition not found: 2.7"
+}
+
 @test "sorting Python versions" {
   export PYTHON_BUILD_ROOT="$TMP"
   mkdir -p "${PYTHON_BUILD_ROOT}/share/python-build"

plugins/python-build/test/hooks.bats

@@ -15,6 +15,7 @@ after_install 'echo after: \$STATUS'
 OUT
   stub pyenv-hooks "install : echo '$HOOK_PATH'/install.bash"
   stub pyenv-rehash "echo rehashed"
+  stub pyenv-latest false
 
   definition="${TMP}/3.6.2"
   cat > "$definition" <<<"echo python-build"

plugins/python-build/test/pyenv.bats

@@ -10,6 +10,7 @@ setup() {
 
 stub_python_build() {
   stub python-build "--lib : $BATS_TEST_DIRNAME/../bin/python-build --lib" "$@"
+  stub pyenv-latest " : false"
 }
 
 @test "install proper" {
@@ -23,6 +24,19 @@ stub_python_build() {
   unstub pyenv-rehash
 }
 
+@test "install resolves a prefix" {
+  stub_python_build 'echo python-build "$@"'
+  stub pyenv-latest '-q -k 3.4 : echo 3.4.2'
+  pyenv-latest || true  # pass through the stub entry added by stub_python_build
+
+  run pyenv-install 3.4
+  assert_success "python-build 3.4.2 ${PYENV_ROOT}/versions/3.4.2"
+
+  unstub python-build
+  unstub pyenv-hooks
+  unstub pyenv-rehash
+}
+
 @test "install pyenv local version by default" {
   stub_python_build 'echo python-build "$1"'
   stub pyenv-local 'echo 3.4.2'

plugins/python-build/test/test_helper.bash

@@ -139,3 +139,29 @@ assert_output_contains() {
     } | flunk
   }
 }
+
+# Output a modified PATH that ensures that the given executable is not present,
+# but in which system utils necessary for pyenv operation are still available.
+path_without() {
+  local path=":${PATH}:"
+  for exe; do 
+    local found alt util
+    for found in $(PATH="$path" type -aP "$exe"); do
+      found="${found%/*}"
+      if [ "$found" != "${PYENV_ROOT}/shims" ]; then
+        alt="${PYENV_TEST_DIR}/$(echo "${found#/}" | tr '/' '-')"
+        mkdir -p "$alt"
+        for util in bash head cut readlink greadlink; do
+          if [ -x "${found}/$util" ]; then
+            ln -s "${found}/$util" "${alt}/$util"
+          fi
+        done
+        path="${path/:${found}:/:${alt}:}"
+      fi
+    done
+  done
+  path="${path#:}"
+  path="${path%:}"
+  echo "$path"
+}
+