test(backend): parallelize isolated fixtures [CI] [SKIP TESTS]

backend/tests/MoShiro.Backend.Tests/TestReleaseKey.cs

@@ -11,11 +11,26 @@ namespace MoShiro.Backend.Tests;
 public sealed class TestReleaseKey : IReleaseKey
 {
     private static readonly ECDsa s_key = ECDsa.Create(ECCurve.NamedCurves.nistP256);
+    private static readonly object s_gate = new();
 
     public static TestReleaseKey Instance { get; } = new();
 
-    public string Pem => s_key.ExportSubjectPublicKeyInfoPem();
+    public string Pem
+    {
+        get
+        {
+            lock (s_gate)
+            {
+                return s_key.ExportSubjectPublicKeyInfoPem();
+            }
+        }
+    }
 
-    public static string Sign(string manifest) =>
-        Convert.ToBase64String(s_key.SignData(Encoding.UTF8.GetBytes(manifest), HashAlgorithmName.SHA256, DSASignatureFormat.Rfc3279DerSequence));
+    public static string Sign(string manifest)
+    {
+        lock (s_gate)
+        {
+            return Convert.ToBase64String(s_key.SignData(Encoding.UTF8.GetBytes(manifest), HashAlgorithmName.SHA256, DSASignatureFormat.Rfc3279DerSequence));
+        }
+    }
 }