dnfjson: detect/error if no repositories are defined

This commit adds an error message if no repositories are
defined in the dnfjson query. We had the issue in
https://github.com/osbuild/bootc-image-builder/issues/922
that in a RHEL bootc-container no repositories are defined.

Here the error is quite confusing, as it complains about
error marking packages which is technically correct but
hides the root of the problem.

With this detect we can construct a more useful error
message in the higher layers.

tools/osbuild-depsolve-dnf

@@ -13,7 +13,7 @@ import os.path
 import sys
 import tempfile
 
-from osbuild.solver import GPGKeyReadError, MarkingError, DepsolveError, RepoError, InvalidRequestError
+from osbuild.solver import GPGKeyReadError, MarkingError, DepsolveError, NoReposError, RepoError, InvalidRequestError
 
 # Load the solver configuration
 config = {"use_dnf5": False}
@@ -77,6 +77,11 @@ def solve(request, cache_dir):
                 "kind": "RepoError",
                 "reason": f"There was a problem reading a repository: {e}"
             }
+        except NoReposError as e:
+            return None, {
+                "kind": "NoReposError",
+                "reason": f"There was a problem finding repositories: {e}"
+            }
         except MarkingError as e:
             printe("error install_specs")
             return None, {

tools/test/test_depsolve.py

@@ -1865,3 +1865,28 @@ def test_depsolve_result_api(tmp_path, repo_servers):
         "data",
         "path",
     ]
+
+
+@pytest.mark.parametrize("dnf_config, detect_fn", [
+    ({}, assert_dnf),
+    ({"use_dnf5": False}, assert_dnf),
+    ({"use_dnf5": True}, assert_dnf5),
+], ids=["no-config", "dnf4", "dnf5"])
+def test_depsolve_no_repos(tmp_path, dnf_config, detect_fn):
+    try:
+        detect_fn()
+    except RuntimeError as e:
+        pytest.skip(str(e))
+
+    transactions = [
+        {
+            "package-specs": [
+                "filesystem",
+                "pkg-with-no-deps"
+            ],
+        },
+    ]
+    res, exit_code = depsolve(transactions, tmp_path.as_posix(), dnf_config, root_dir=tmp_path.as_posix())
+    assert exit_code == 1
+    assert res["kind"] == "NoReposError"
+    assert "There are no enabled repositories" in res["reason"]