List missing streams in exception message.

Fixes: https://pagure.io/fm-orchestrator/issue/1574

module_build_service/common/resolve.py

@@ -141,7 +141,7 @@ def get_base_module_mmds(db_session, mmd):
     from module_build_service.common import models
 
     seen = set()
-    ret = {"ready": [], "garbage": []}
+    ret = {"ready": [], "garbage": [], "missing": []}
 
     resolver = GenericResolver.create(db_session, conf)
     for deps in mmd.get_dependencies():
@@ -172,6 +172,7 @@ def get_base_module_mmds(db_session, mmd):
                 # zero or one module build.
                 mmds = resolver.get_module_modulemds(name, stream)
                 if not mmds:
+                    ret["missing"] += [ns]
                     continue
                 base_mmd = mmds[0]
 

module_build_service/web/mse.py

@@ -187,9 +187,13 @@ def get_mmds_required_by_module_recursively(
     base_module_mmds = get_base_module_mmds(db_session, mmd)
     if not base_module_mmds["ready"]:
         base_module_choices = " or ".join(conf.base_module_names)
+        missing = base_module_mmds["missing"]
+        missing_msg = ""
+        if missing:
+            missing_msg = "  Missing streams are ({}).".format(", ".join(missing))
         raise UnprocessableEntity(
-            "None of the base module ({}) streams in the buildrequires section could be found"
-            .format(base_module_choices)
+            "None of the base module ({}) streams in the buildrequires section could be found.{}"
+            .format(base_module_choices, missing_msg)
         )
 
     # Add base modules to `mmds`.

tests/test_common/test_resolve.py

@@ -100,6 +100,7 @@ class TestResolve:
         expected = {}
         expected["ready"] = {"platform:foo29", "platform:foo30"}
         expected["garbage"] = {"platform:foo28"}
+        expected["missing"] = set()
 
         # Verify no duplicates were returned before doing set operations
         assert len(mmds) == len(expected)

tests/test_web/test_views.py

@@ -1035,7 +1035,7 @@ class TestSubmitBuild:
             "status": 422,
             "message": (
                 "None of the base module (platform) streams in the buildrequires section "
-                "could be found"
+                "could be found.  Missing streams are (platform:Go)."
             ),
             "error": "Unprocessable Entity",
         }
@@ -2395,7 +2395,7 @@ class TestSubmitBuild:
             "status": 422,
             "message": (
                 "None of the base module (platform) streams in the buildrequires "
-                "section could be found"
+                "section could be found.  Missing streams are (platform:28.0.0)."
             ),
         }
         assert rv.status_code == 422