Fix candidate stanza resolution for stable streams

cmd/release-controller/sync_verify.go

@@ -187,12 +187,11 @@ func (c *Controller) resolveUpgradeRelease(upgradeRelease *releasecontroller.Upg
 		pullSpec := releasecontroller.ReleasePullSpec(r, latest)
 		return tag, pullSpec, nil
 	} else if upgradeRelease.Candidate != nil {
-		// create blank semver.Range
 		var constraint semver.Range
-		stream := fmt.Sprintf("%s.0-0.%s%s", upgradeRelease.Candidate.Version, upgradeRelease.Candidate.Stream, TrimPrefixes(release.Config.To, "release-5", "release"))
-		r, latest, err := releasecontroller.LatestForStream(c.parsedReleaseConfigCache, c.eventRecorder, c.releaseLister, c.releasePayloadLister, stream, constraint, upgradeRelease.Candidate.Relative, "")
+		streamName, versionPrefix := candidateStreamName(upgradeRelease.Candidate.Version, upgradeRelease.Candidate.Stream, release.Config.To)
+		r, latest, err := releasecontroller.LatestForStream(c.parsedReleaseConfigCache, c.eventRecorder, c.releaseLister, c.releasePayloadLister, streamName, constraint, upgradeRelease.Candidate.Relative, versionPrefix)
 		if err != nil {
-			return "", "", fmt.Errorf("failed to get latest tag for stream %s: %w", stream, err)
+			return "", "", fmt.Errorf("failed to get latest tag for stream %s: %w", streamName, err)
 		}
 		tag := latest.Name
 		pullSpec := releasecontroller.ReleasePullSpec(r, latest)
@@ -217,3 +216,16 @@ func TrimPrefixes(s string, prefixes ...string) string {
 	}
 	return s
 }
+
+// candidateStreamName returns the release stream name and an optional version
+// prefix filter for a candidate upgrade source. Nightly and CI streams use
+// names like "4.22.0-0.nightly"; stable streams use "N-stable" (e.g. "4-stable")
+// and need the version prefix to filter to the requested minor version.
+func candidateStreamName(version, stream, configTo string) (streamName, versionPrefix string) {
+	suffix := TrimPrefixes(configTo, "release-5", "release")
+	if stream == "stable" {
+		major, _, _ := strings.Cut(version, ".")
+		return fmt.Sprintf("%s-stable%s", major, suffix), version + "."
+	}
+	return fmt.Sprintf("%s.0-0.%s%s", version, stream, suffix), ""
+}

cmd/release-controller/sync_verify_test.go

@@ -116,6 +116,94 @@ var reference4Preview = releasecontroller.StableRelease{
 	}},
 }
 
+func TestCandidateStreamName(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name                  string
+		version               string
+		stream                string
+		configTo              string
+		expectedStreamName    string
+		expectedVersionPrefix string
+	}{
+		{
+			name:                  "stable stream, empty configTo",
+			version:               "4.22",
+			stream:                "stable",
+			configTo:              "",
+			expectedStreamName:    "4-stable",
+			expectedVersionPrefix: "4.22.",
+		},
+		{
+			name:                  "stable stream, configTo=release",
+			version:               "4.22",
+			stream:                "stable",
+			configTo:              "release",
+			expectedStreamName:    "4-stable",
+			expectedVersionPrefix: "4.22.",
+		},
+		{
+			name:                  "stable stream, major version 5",
+			version:               "5.1",
+			stream:                "stable",
+			configTo:              "",
+			expectedStreamName:    "5-stable",
+			expectedVersionPrefix: "5.1.",
+		},
+		{
+			name:                  "stable stream, arm64 suffix",
+			version:               "4.22",
+			stream:                "stable",
+			configTo:              "release-arm64",
+			expectedStreamName:    "4-stable-arm64",
+			expectedVersionPrefix: "4.22.",
+		},
+		{
+			name:                  "nightly stream, configTo=release",
+			version:               "4.22",
+			stream:                "nightly",
+			configTo:              "release",
+			expectedStreamName:    "4.22.0-0.nightly",
+			expectedVersionPrefix: "",
+		},
+		{
+			name:                  "nightly stream, configTo=release-5",
+			version:               "4.22",
+			stream:                "nightly",
+			configTo:              "release-5",
+			expectedStreamName:    "4.22.0-0.nightly",
+			expectedVersionPrefix: "",
+		},
+		{
+			name:                  "ci stream",
+			version:               "4.22",
+			stream:                "ci",
+			configTo:              "release",
+			expectedStreamName:    "4.22.0-0.ci",
+			expectedVersionPrefix: "",
+		},
+		{
+			name:                  "nightly stream, arm64 suffix",
+			version:               "4.22",
+			stream:                "nightly",
+			configTo:              "release-arm64",
+			expectedStreamName:    "4.22.0-0.nightly-arm64",
+			expectedVersionPrefix: "",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			streamName, versionPrefix := candidateStreamName(tc.version, tc.stream, tc.configTo)
+			if streamName != tc.expectedStreamName {
+				t.Errorf("Expected stream name %q, got %q", tc.expectedStreamName, streamName)
+			}
+			if versionPrefix != tc.expectedVersionPrefix {
+				t.Errorf("Expected version prefix %q, got %q", tc.expectedVersionPrefix, versionPrefix)
+			}
+		})
+	}
+}
+
 func TestFindLatestStableForVersion(t *testing.T) {
 	t.Parallel()
 	testCases := []struct {