tests: add tests for Arch and Chroot types (MR 2252)

Add some exhaustive unit testing to validate that these types behave as
expected.

And fix a few bugs uncovered by the tests.

Signed-off-by: Caleb Connolly <caleb@postmarketos.org>

pmb/core/test_chroot.py

@@ -0,0 +1,57 @@
+import pytest
+
+from .arch import Arch
+from .context import get_context
+from .chroot import Chroot, ChrootType
+
+def test_valid_chroots(pmb_args, mock_devices_find_path):
+    """Test that Chroot objects work as expected"""
+
+    work = get_context().config.work
+
+    chroot = Chroot.native()
+    assert chroot.type == ChrootType.NATIVE
+    assert chroot.name == ""
+    assert chroot.arch in Arch.supported()
+    assert not chroot.exists()  # Shouldn't be created
+    assert chroot.path == work / "chroot_native"
+    assert str(chroot) == "native"
+    
+    chroot = Chroot.buildroot(Arch.aarch64)
+    assert chroot.type == ChrootType.BUILDROOT
+    assert chroot.name == "aarch64"
+    assert chroot.arch == Arch.aarch64
+    assert not chroot.exists() # Shouldn't be created
+    assert chroot.path == work / "chroot_buildroot_aarch64"
+    assert str(chroot) == "buildroot_aarch64"
+
+    # FIXME: implicily assumes that we're mocking the qemu-amd64 deviceinfo
+    chroot = Chroot(ChrootType.ROOTFS, "qemu-amd64")
+    assert chroot.type == ChrootType.ROOTFS
+    assert chroot.name == "qemu-amd64"
+    assert chroot.arch == Arch.x86_64
+    assert not chroot.exists() # Shouldn't be created
+    assert chroot.path == work / "chroot_rootfs_qemu-amd64"
+    assert str(chroot) == "rootfs_qemu-amd64"
+
+
+# mypy: ignore-errors
+def test_invalid_chroots(pmb_args):
+    """Test that we can't create invalid chroots."""
+
+    with pytest.raises(ValueError) as excinfo:
+        Chroot(ChrootType.BUILDROOT, "BAD_ARCH")
+    assert str(excinfo.value) == "Invalid buildroot suffix: 'BAD_ARCH'"
+
+    with pytest.raises(ValueError) as excinfo:
+        Chroot(ChrootType.NATIVE, "aarch64")
+    assert str(excinfo.value) == "The native suffix can't have a name but got: 'aarch64'"
+
+    with pytest.raises(ValueError) as excinfo:
+        Chroot("beep boop")
+    assert str(excinfo.value) == "Invalid chroot type: 'beep boop'"
+
+    with pytest.raises(ValueError) as excinfo:
+        Chroot(5)
+    assert str(excinfo.value) == "Invalid chroot type: '5'"
+