Add add_mock_package

micropip/__init__.py

@@ -1,9 +1,9 @@
 from ._micropip import _list as list
-from ._micropip import freeze, install
+from ._micropip import add_mock_package, freeze, install
 
 try:
     from ._version import __version__
 except ImportError:
     pass
 
-__all__ = ["install", "list", "freeze", "__version__"]
+__all__ = ["install", "list", "freeze", "add_mock_package", "__version__"]

micropip/_micropip.py

@@ -2,6 +2,8 @@
 import hashlib
 import importlib
 import json
+import os
+import site
 import warnings
 from asyncio import gather
 from dataclasses import dataclass, field
@@ -10,6 +12,7 @@
 from importlib.metadata import version as importlib_version
 from pathlib import Path
 from sysconfig import get_platform
+from textwrap import dedent
 from typing import IO, Any
 from urllib.parse import ParseResult, urlparse
 from zipfile import ZipFile
@@ -692,3 +695,72 @@ def _list():
             source_ = pkg_source
         packages[name] = PackageMetadata(name=name, version=version, source=source_)
     return packages
+
+
+def add_mock_package(name, version, *, modules=None):
+    """
+       Add a mock version of a package to the package dictionary.
+
+       This means that if it is a dependency, it is skipped on install.
+
+       By default a single empty module is installed with the same
+       name as the package. You can alternatively give one or more modules to make a
+       set of named modules.
+
+       The modules parameter is a dictionary mapping module name to module text.
+
+        e.g.
+       ``
+       {
+          mylovely_module:'''
+            def module_method(an_argument):
+                print("This becomes a module level argument")
+            module_value = "this value becomes a module level variable"
+
+            print("This is run on import of module")
+          '''
+       }
+
+
+       ``
+
+    Parameters
+    ----------
+    name : ``str ``
+
+        Package name to add
+
+    modules : ``Optional(dict) ``
+
+        Dictionary of module_name:string pairs.
+        The string contains the source of the mock module or is blank for
+        an empty module.
+    """
+    if modules is None:
+        # make a single mock module with this name
+        modules = {name: ""}
+    # make empty mock modules with the requested names in user site packages
+    site_packages = Path(site.getusersitepackages())
+    metadata_file = site_packages / (name + "-" + version + ".egg-info")
+    with open(metadata_file, "w") as mf:
+
+        mf.write(
+            f"""Metadata-Version: 1.1
+Name: {name}
+Version: {version}
+Summary: {name} mock module generated by micropip
+Author-email: {name}@micro.pip.non-working-fake-host
+"""
+        )
+        for n, s in modules.items():
+            mf.write(f"Provides:{n}\n")
+
+            if s is None:
+                s = ""
+            s = dedent(s)
+            path_parts = n.split(".")
+            dir_path = Path(site_packages, *path_parts)
+            os.makedirs(dir_path, exist_ok=True)
+            init_file = dir_path / "__init__.py"
+            with open(init_file, "w") as f:
+                f.write(s)

tests/test_micropip.py

@@ -934,3 +934,45 @@ def test_check_compatible(mock_platform, interp, abi, arch, ctx):
     wheel_name = f"{pkg}-{interp}-{abi}-{arch}.whl"
     with ctx:
         WheelInfo.from_url(wheel_name).check_compatible()
+
+
+def test_add_mock_package(monkeypatch, capsys):
+    import site
+    from importlib.metadata import version as importlib_version
+
+    from micropip._micropip import add_mock_package
+
+    with TemporaryDirectory() as tmpdirname:
+
+        def _getusersitepackages():
+            return tmpdirname
+
+        monkeypatch.setattr(site, "getusersitepackages", _getusersitepackages)
+        monkeypatch.setattr(sys, "path", [tmpdirname])
+        add_mock_package("test_1", "1.0.0")
+        add_mock_package(
+            "test_2",
+            "1.2.0",
+            modules={
+                "t1": "print('hi from t1')",
+                "t2": """
+            def fn():
+                print("Hello from fn")
+            """,
+            },
+        )
+        import t1
+
+        dir(t1)
+        import t2
+
+        dir(t2)
+        import test_1
+
+        dir(test_1)
+
+        t2.fn()
+        assert importlib_version("test_2") == "1.2.0"
+    captured = capsys.readouterr()
+    assert captured.out.find("hi from t1") != -1
+    assert captured.out.find("Hello from fn") != -1