Add support for pending merges (#1533)

* Add pending state

* Add pending logic

* Assert on `.expected`

* Remove extraneous state check

* Pull out combined merge status logic

Classes/Issues/Merge/IssueMergeSectionController.swift

@@ -72,13 +72,10 @@ MergeButtonDelegate {
         var viewModels = [ListDiffable]()
 
         if object.contexts.count > 0 {
-            let success = object.contexts.reduce(true, { $0 && $1.state == .success })
-            viewModels.append(IssueMergeSummaryModel(
-                title: success ?
-                    NSLocalizedString("All checks passed", comment: "")
-                    : NSLocalizedString("Some checks failed", comment: ""),
-                state: success ? .success : .failure
-            ))
+            let states = object.contexts.map { $0.state }
+            let (state, stateDescription) = combinedMergeStatus(for: states)
+            
+            viewModels.append(IssueMergeSummaryModel(title: stateDescription, state: state))
         }
 
         viewModels += object.contexts as [ListDiffable]
@@ -187,4 +184,28 @@ MergeButtonDelegate {
         viewController?.present(alert, animated: trueUnlessReduceMotionEnabled)
     }
 
+    // MARK: Private
+    private func combinedMergeStatus(for states: [StatusState]) -> (IssueMergeSummaryModel.State, String) {
+        let state: IssueMergeSummaryModel.State
+        let stateDescription: String
+        let failureDescription = NSLocalizedString("Some checks failed", comment: "")
+        switch states {
+        case let states where states.contains(.failure) || states.contains(.error):
+            state = .failure
+            stateDescription = failureDescription
+        case let states where states.contains(.pending):
+            state = .pending
+            stateDescription = NSLocalizedString("Merge status pending", comment: "")
+        case let states where states.reduce(true, { $0 && $1 == .success }):
+            state = .success
+            stateDescription = NSLocalizedString("All checks passed", comment: "")
+        default:
+            assert(false, "This should only occur when any of the `states` are of type `.expected`, which we have no clue of when it is used. The documentation (https://developer.github.com/v4/enum/statusstate/) doesn't answer that question either.")
+            state = .failure
+            stateDescription = failureDescription
+        }
+
+        return (state, stateDescription)
+    }
+
 }

Classes/Issues/Merge/IssueMergeSummaryCell.swift

@@ -61,7 +61,7 @@ final class IssueMergeSummaryCell: IssueCommentBaseCell, ListBindable {
         case .failure:
             imageViewBackground = Styles.Colors.Red.medium.color
             iconName = "merge-x"
-        case .warning:
+        case .warning, .pending:
             imageViewBackground = Styles.Colors.Gray.medium.color
             iconName = "merge-alert"
         }

Classes/Issues/Merge/IssueMergeSummaryModel.swift

@@ -13,6 +13,7 @@ final class IssueMergeSummaryModel: ListDiffable {
 
     enum State: Int {
         case success
+        case pending
         case failure
         case warning
     }