Add support for install_command virtualenv settings (#1886)

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

6 files changed, 56 insertions, 22 deletions

diff --git a/src/tox/config/of_type.py b/src/tox/config/of_type.py
index ba369e62..3c42dc49 100644
--- a/src/tox/config/of_type.py
+++ b/src/tox/config/of_type.py
@@ -70,7 +70,7 @@ class ConfigDynamicDefinition(ConfigDefinition[T]):
         env_name: Optional[str],
         of_type: Type[T],
         default: Union[Callable[["Config", Optional[str]], T], T],
-        post_process: Optional[Callable[[T, "Config"], T]] = None,
+        post_process: Optional[Callable[[T], T]] = None,
         kwargs: Optional[Mapping[str, Any]] = None,
     ) -> None:
         super().__init__(keys, desc, env_name)
@@ -96,7 +96,7 @@ class ConfigDynamicDefinition(ConfigDefinition[T]):
             else:
                 value = self.default(conf, self.env_name) if callable(self.default) else self.default
             if self.post_process is not None:
-                value = self.post_process(value, conf)  # noqa
+                value = self.post_process(value)  # noqa
             self._cache = value
         return cast(T, self._cache)
 
diff --git a/src/tox/config/sets.py b/src/tox/config/sets.py
index 08735f62..6e31a664 100644
--- a/src/tox/config/sets.py
+++ b/src/tox/config/sets.py
@@ -44,7 +44,7 @@ class ConfigSet:
         of_type: Type[V],
         default: Union[Callable[["Config", Optional[str]], V], V],
         desc: str,
-        post_process: Optional[Callable[[V, "Config"], V]] = None,
+        post_process: Optional[Callable[[V], V]] = None,
         kwargs: Optional[Mapping[str, Any]] = None,
     ) -> ConfigDynamicDefinition[V]:
         """
@@ -149,7 +149,7 @@ class EnvConfigSet(ConfigSet):
         super().__init__(conf, name=name)
         self.default_set_env_loader: Callable[[], Mapping[str, str]] = lambda: {}
 
-        def set_env_post_process(values: SetEnv, config: "Config") -> SetEnv:
+        def set_env_post_process(values: SetEnv) -> SetEnv:
             values.update_if_not_present(self.default_set_env_loader())
             return values
 
diff --git a/src/tox/provision.py b/src/tox/provision.py
index 2a00acdb..9710a70e 100644
--- a/src/tox/provision.py
+++ b/src/tox/provision.py
@@ -11,8 +11,7 @@ from packaging.utils import canonicalize_name
 from packaging.version import Version
 
 from tox.config.loader.memory import MemoryLoader
-from tox.config.main import Config
-from tox.config.sets import ConfigSet
+from tox.config.sets import CoreConfigSet
 from tox.execute.api import StdinSource
 from tox.plugin.impl import impl
 from tox.session.state import State
@@ -45,7 +44,7 @@ def tox_add_option(parser: ArgumentParser) -> None:
 
 
 @impl
-def tox_add_core_config(core: ConfigSet) -> None:
+def tox_add_core_config(core: CoreConfigSet) -> None:
     core.add_config(
         keys=["min_version", "minversion"],
         of_type=Version,
@@ -60,8 +59,8 @@ def tox_add_core_config(core: ConfigSet) -> None:
         desc="Name of the virtual environment used to provision a tox.",
     )
 
-    def add_tox_requires_min_version(requires: List[Requirement], conf: Config) -> List[Requirement]:
-        min_version: Version = conf.core["min_version"]
+    def add_tox_requires_min_version(requires: List[Requirement]) -> List[Requirement]:  # noqa
+        min_version: Version = core["min_version"]
         requires.append(Requirement(f"tox >= {min_version.public}"))
         return requires
 
diff --git a/src/tox/tox_env/api.py b/src/tox/tox_env/api.py
index 0555a286..5b9391c7 100644
--- a/src/tox/tox_env/api.py
+++ b/src/tox/tox_env/api.py
@@ -12,7 +12,6 @@ from io import BytesIO
 from pathlib import Path
 from typing import TYPE_CHECKING, Dict, Iterator, List, Optional, Sequence, Tuple, Union, cast
 
-from tox.config.main import Config
 from tox.config.set_env import SetEnv
 from tox.config.sets import CoreConfigSet, EnvConfigSet
 from tox.execute.api import Execute, ExecuteStatus, Outcome, StdinSource
@@ -94,7 +93,7 @@ class ToxEnv(ABC):
         )
         self.conf.default_set_env_loader = self.default_set_env
 
-        def pass_env_post_process(values: List[str], config: Config) -> List[str]:
+        def pass_env_post_process(values: List[str]) -> List[str]:
             values.extend(self.default_pass_env())
             return sorted(list({k: None for k in values}.keys()))
 
diff --git a/src/tox/tox_env/python/virtual_env/api.py b/src/tox/tox_env/python/virtual_env/api.py
index 5f4afe98..ac0902cf 100644
--- a/src/tox/tox_env/python/virtual_env/api.py
+++ b/src/tox/tox_env/python/virtual_env/api.py
@@ -12,7 +12,9 @@ from virtualenv.run.session import Session
 
 from tox.config.cli.parser import DEFAULT_VERBOSITY, Parsed
 from tox.config.loader.str_convert import StrConvert
+from tox.config.main import Config
 from tox.config.sets import CoreConfigSet, EnvConfigSet
+from tox.config.types import Command
 from tox.execute.api import Execute, Outcome, StdinSource
 from tox.execute.local_sub_process import LocalSubProcessExecutor
 from tox.journal import EnvJournal
@@ -66,6 +68,33 @@ class VirtualEnv(Python, ABC):
             desc="install the latest available pre-release (alpha/beta/rc) of dependencies without a specified version",
         )
 
+        self.conf.add_config(
+            keys=["install_command"],
+            of_type=Command,
+            default=self.default_install_command,
+            post_process=self.post_process_install_command,
+            desc="install the latest available pre-release (alpha/beta/rc) of dependencies without a specified version",
+        )
+
+    def post_process_install_command(self, cmd: Command) -> Command:
+        install_command = cmd.args
+        pip_pre: bool = self.conf["pip_pre"]
+        try:
+            opts_at = install_command.index("{opts}")
+        except ValueError:
+            if pip_pre:
+                install_command.append("--pre")
+        else:
+            if pip_pre:
+                install_command[opts_at] = "--pre"
+            else:
+                install_command.pop(opts_at)
+        return cmd
+
+    def default_install_command(self, conf: Config, env_name: Optional[str]) -> Command:  # noqa
+        cmd = Command(["python", "-I", "-m", "pip", "install", "{opts}", "{packages}"])
+        return self.post_process_install_command(cmd)
+
     def setup(self) -> None:
         with self._cache.compare({"version": virtualenv_version}, VirtualEnv.__name__) as (eq, old):
             if eq is False and old is not None:  # if changed create
@@ -153,23 +182,30 @@ class VirtualEnv(Python, ABC):
     ) -> None:
         if not packages:
             return
-        install_command = self.base_install_cmd
+
+        args: List[str] = []
         if no_deps:
-            install_command.append("--no-deps")
+            args.append("--no-deps")
         if force_reinstall:
-            install_command.append("--force-reinstall")
+            args.append("--force-reinstall")
         if develop is True:
-            install_command.extend(("--no-build-isolation", "-e"))
+            args.extend(("--no-build-isolation", "-e"))
+        args.extend(str(i) for i in packages)
+        install_command = self.build_install_cmd(args)
 
-        install_command.extend(str(i) for i in packages)
         result = self.perform_install(install_command, f"install_{of_type}")
         result.assert_success()
 
-    @property
-    def base_install_cmd(self) -> List[str]:
-        result = [str(self.creator.exe), "-I", "-m", "pip", "install"]
-        if self.conf["pip_pre"]:
-            result.append("--pre")
+    def build_install_cmd(self, args: Sequence[str]) -> List[str]:
+        cmd: Command = self.conf["install_command"]
+        install_command = cmd.args
+        try:
+            opts_at = install_command.index("{packages}")
+        except ValueError:
+            opts_at = len(install_command)
+        result = install_command[:opts_at]
+        result.extend(args)
+        result.extend(install_command[opts_at + 1 :])
         return result
 
     def perform_install(self, install_command: Sequence[str], run_id: str) -> Outcome:
diff --git a/src/tox/tox_env/python/virtual_env/runner.py b/src/tox/tox_env/python/virtual_env/runner.py
index d724aae7..ed712ce3 100644
--- a/src/tox/tox_env/python/virtual_env/runner.py
+++ b/src/tox/tox_env/python/virtual_env/runner.py
@@ -121,7 +121,7 @@ class VirtualEnvRunner(VirtualEnv, PythonRun):
         }
 
     def install_requirement_file(self, path: Path) -> None:
-        install_command = self.base_install_cmd + ["-r", str(path)]
+        install_command = self.build_install_cmd(["-r", str(path)])
         result = self.perform_install(install_command, "install_deps")
         result.assert_success()