artifactcache.py: Fix misleading error message when using % cache quotajennis/quota_declaration_fix

Due to the changed Exception message, this patch also changes
the test_parse_size_over_1024T test in misc.py

2 files changed, 15 insertions, 7 deletions

diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index 06a2b84e0..b0324462c 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -937,15 +937,22 @@ class ArtifactCache():
                             "Invalid cache quota ({}): ".format(utils._pretty_size(cache_quota)) +
                             "BuildStream requires a minimum cache quota of 2G.")
         elif cache_quota > cache_size + available_space:  # Check maximum
+            if '%' in self.context.config_cache_quota:
+                available = (available_space / (stat.f_blocks * stat.f_bsize)) * 100
+                available = '{}% of total disk space'.format(round(available, 1))
+            else:
+                available = utils._pretty_size(available_space)
+
             raise LoadError(LoadErrorReason.INVALID_DATA,
                             ("Your system does not have enough available " +
                              "space to support the cache quota specified.\n" +
-                             "You currently have:\n" +
-                             "- {used} of cache in use at {local_cache_path}\n" +
-                             "- {available} of available system storage").format(
-                                 used=utils._pretty_size(cache_size),
-                                 local_cache_path=self.context.artifactdir,
-                                 available=utils._pretty_size(available_space)))
+                             "\nYou have specified a quota of {quota} total disk space.\n" +
+                             "- The filesystem containing {local_cache_path} only " +
+                             "has: {available_size} available.")
+                            .format(
+                                quota=self.context.config_cache_quota,
+                                local_cache_path=self.context.artifactdir,
+                                available_size=available))
 
         # Place a slight headroom (2e9 (2GB) on the cache_quota) into
         # cache_quota to try and avoid exceptions.
diff --git a/tests/utils/misc.py b/tests/utils/misc.py
index ae584e4d5..7df08aec5 100644
--- a/tests/utils/misc.py
+++ b/tests/utils/misc.py
@@ -27,4 +27,5 @@ def test_parse_size_over_1024T(cli, tmpdir):
     patched_statvfs = mock_os.mock_statvfs(f_bavail=bavail, f_bsize=BLOCK_SIZE)
     with mock_os.monkey_patch("statvfs", patched_statvfs):
         result = cli.run(project, args=["build", "file.bst"])
-        assert "1025T of available system storage" in result.stderr
+        failure_msg = 'Your system does not have enough available space to support the cache quota specified.'
+        assert failure_msg in result.stderr