Add filter by colors method to GRDBCard requests

Author: ioboi

CubeSight/Database/Model/DerivableRequest+GRDBCard.swift

@@ -0,0 +1,11 @@
+import Foundation
+import GRDB
+
+extension DerivableRequest<GRDBCard> {
+  func filter(colors: [ScryfallColor]) -> Self {
+    self.joining(
+      required: GRDBCard.colors.filter { colors.contains($0.color) }
+    )
+    .distinct()
+  }
+}

CubeSightTests/CardColorTests.swift

@@ -25,11 +25,7 @@ struct CardColorTests {
     let db = try await makeAppDatabase()
 
     let count = try await db.reader.read { db in
-      try GRDBCard.joining(
-        required: GRDBCard.colors.filter { tc.colors.contains($0.color) }
-      )
-      .distinct()
-      .fetchCount(db)
+      return try GRDBCard.all().filter(colors: tc.colors).fetchCount(db)
     }
     #expect(count == tc.expectedCount)
   }