test instrumentation: add dependency injected toml content to read_pyproject

Author: RonnyPfannschmidt

src/setuptools_scm/_integration/pyproject_reading.py

@@ -174,6 +174,7 @@ def read_pyproject(
     tool_name: str = DEFAULT_TOOL_NAME,
     canonical_build_package_name: str = "setuptools-scm",
     _given_result: _t.GivenPyProjectResult = None,
+    _given_definition: TOML_RESULT | None = None,
 ) -> PyProjectData:
     """Read and parse pyproject configuration.
 
@@ -195,7 +196,10 @@ def read_pyproject(
         if isinstance(_given_result, (InvalidTomlError, FileNotFoundError)):
             raise _given_result
 
-    defn = read_toml_content(path)
+    if _given_definition is not None:
+        defn = _given_definition
+    else:
+        defn = read_toml_content(path)
 
     requires: list[str] = defn.get("build-system", {}).get("requires", [])
     is_required = has_build_package(requires, canonical_build_package_name)

testing/test_pyproject_reading.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from pathlib import Path
+from unittest.mock import Mock
 
 import pytest
 
@@ -108,3 +109,20 @@ def test_invalid_requirement_string(self) -> None:
         assert (
             has_build_package_with_extra(requires, "setuptools-scm", "simple") is False
         )
+
+
+def test_read_pyproject_with_given_definition(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test that read_pyproject reads existing files correctly."""
+    monkeypatch.setattr(
+        "setuptools_scm._integration.pyproject_reading.read_toml_content",
+        Mock(side_effect=FileNotFoundError("this test should not read")),
+    )
+
+    res = read_pyproject(
+        _given_definition={
+            "build-system": {"requires": ["setuptools-scm[simple]"]},
+            "project": {"name": "test-package", "dynamic": ["version"]},
+        }
+    )
+
+    assert res.should_infer()