Add test helpers, rewrite integration tests

riotfile.py

@@ -12,7 +12,7 @@
             },
             pys=[3.6, 3.7, 3.8, 3.9],
             pkgs={
-                "pytest": latest,
+                "pytest": "==6.1.2",
                 "pytest-cov": latest,
                 "mock": latest,
             },

tests/proctest.py

@@ -0,0 +1,73 @@
+import dataclasses
+import os
+import subprocess
+import sys
+import tempfile
+import typing as t
+
+
+if t.TYPE_CHECKING or sys.version_info[:2] >= (3, 9):
+    _T_CompletedProcess = subprocess.CompletedProcess[str]
+else:
+    _T_CompletedProcess = subprocess.CompletedProcess
+
+_T_Path = t.Union[str, "os.PathLike[t.Any]"]
+
+
+@dataclasses.dataclass(frozen=True)
+class ProcResult:
+    proc: _T_CompletedProcess = dataclasses.field(repr=False)
+
+    @property
+    def stdout(self) -> str:
+        return self.proc.stdout
+
+    @property
+    def stderr(self) -> str:
+        return self.proc.stderr
+
+    @property
+    def returncode(self) -> int:
+        return self.proc.returncode
+
+
+class TestDir:
+    def __init__(self):
+        self._tmpdir = tempfile.TemporaryDirectory()
+        self.cwd = self._tmpdir.name
+
+    def __fspath__(self):
+        """Implement Pathlike interface."""
+        return self.cwd
+
+    def cd(self, path: _T_Path) -> None:
+        res_path = path if os.path.isabs(path) else os.path.join(self.cwd, path)
+        self.cwd = res_path
+
+    def mkdir(self, path: _T_Path) -> None:
+        res_path = path if os.path.isabs(path) else os.path.join(self.cwd, path)
+        os.mkdir(res_path)
+
+    def mkfile(self, path: _T_Path, contents: str) -> None:
+        res_path = path if os.path.isabs(path) else os.path.join(self.cwd, path)
+        with open(res_path, "w") as f:
+            f.write(contents)
+
+    def run(
+        self,
+        args: t.Union[str, t.Sequence[str]],
+        env: t.Optional[t.Dict[str, str]] = None,
+        cwd: t.Optional[_T_Path] = None,
+    ) -> ProcResult:
+        if isinstance(args, str):
+            args = args.split(" ")
+
+        p = subprocess.run(
+            args,
+            env=env,
+            encoding=sys.getdefaultencoding(),
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            cwd=self.cwd,
+        )
+        return ProcResult(p)