install only given dev dependency

docs/docs/cli.md

@@ -116,6 +116,16 @@ by passing the `--dev-only` option. Note that `--no-dev` takes priority if both
 poetry install --dev-only
 ```
 
+If not all development dependencies should be installed, but only a specific list, you can do this py passing
+ the `--dev` option. This option can be used multiple times. If only development dependencies should be used, you
+can use this option together with the `--dev-only` option.
+
+```bash
+poetry install --dev black
+poetry install --dev black --dev isort
+poetry install --dev-only --dev black
+```
+
 If you want to remove old dependencies no longer present in the lock file, use the
 `--remove-untracked` option.
 
@@ -156,6 +166,7 @@ option is passed.
 
 * `--no-dev`: Do not install dev dependencies.
 * `--dev-only`: Only install dev dependencies.
+* `--dev`: Only install listed development dependencies.
 * `--no-root`: Do not install the root package (your project).
 * `--dry-run`: Output the operations but do not execute anything (implicitly enables --verbose).
 * `--remove-untracked`: Remove dependencies not presented in the lock file

poetry/console/commands/install.py

@@ -11,6 +11,13 @@ class InstallCommand(InstallerCommand):
  options = [
  option("no-dev", None, "Do not install the development dependencies."),
  option("dev-only", None, "Only install the development dependencies."),
+ option(
+ "dev",
+ None,
+ "Only install listed development dependencies.",
+ flag=False,
+ multiple=True,
+ ),
  option(
  "no-root", None, "Do not install the root package (the current project)."
  ),
@@ -66,6 +73,7 @@ def handle(self): # type: () -> int
  self._installer.extras(extras)
  self._installer.dev_mode(not self.option("no-dev"))
  self._installer.dev_only(self.option("dev-only"))
+ self._installer.dev_dependencies(self.option("dev"))
  self._installer.dry_run(self.option("dry-run"))
  self._installer.remove_untracked(self.option("remove-untracked"))
  self._installer.verbose(self._io.is_verbose())

poetry/installation/installer.py

@@ -63,6 +63,8 @@ def __init__(
 
  self._extras = []
 
+ self._dev_dependencies = []
+
  if executor is None:
  executor = Executor(self._env, self._pool, config, self._io)
 
@@ -150,6 +152,11 @@ def dev_only(self, dev_only=False): # type: (bool) -> Installer
 
  return self
 
+ def dev_dependencies(self, dev_dependencies): # type: (List[str]) -> Installer
+ self._dev_dependencies = dev_dependencies
+
+ return self
+
  def is_dev_only(self): # type: () -> bool
  return self._dev_only
 
@@ -291,6 +298,13 @@ def _do_install(self, local_repo): # type: (Repository) -> int
  root = root.clone()
  del root.requires[:]
 
+ if self._dev_dependencies:
+ root.dev_requires = [
+ package
+ for package in root.dev_requires
+ if package.name in self._dev_dependencies
+ ]
+
  if self._io.is_verbose():
  self._io.write_line("")
  self._io.write_line(