Modify destinations to avoid processing if they don't have settings (#36)

* Added configuration method to insert default settings.

* added settings convenience init.

* Modified destination plugin such that we skip execution if no settings

* added destination enabled/disabled tests.

* Fixed linux test suite.

* return nil if destination isn't able to process event.

Co-authored-by: Brandon Sneed <brandon.sneed@segment.com>

Author: bsneed

Sources/Segment/Configuration.swift

@@ -73,6 +73,12 @@ public extension Configuration {
         return self
     }
 
+    @discardableResult
+    func defaultSettings(_ settings: Settings) -> Configuration {
+        values.defaultSettings = settings
+        return self
+    }
+    
     @discardableResult
     func autoAddSegmentDestination(_ value: Bool) -> Configuration {
         values.autoAddSegmentDestination = value

Sources/Segment/Settings.swift

@@ -21,6 +21,15 @@ public struct Settings: Codable {
         ])
     }
 
+    public init(writeKey: String) {
+        integrations = try! JSON([
+            SegmentDestination.Constants.integrationName.rawValue: [
+                SegmentDestination.Constants.apiKey.rawValue: writeKey,
+                SegmentDestination.Constants.apiHost.rawValue: HTTPClient.getDefaultAPIHost()
+            ]
+        ])
+    }
+    
     public init(from decoder: Decoder) throws {
         let values = try decoder.container(keyedBy: CodingKeys.self)
         self.integrations = try? values.decode(JSON.self, forKey: CodingKeys.integrations)

Sources/Segment/Timeline.swift

@@ -209,37 +209,40 @@ extension DestinationPlugin {
         // This will process plugins (think destination middleware) that are tied
         // to this destination.
 
+        var result: E? = nil
+        
         // For destination plugins, we will always have some kind of `settings`,
         // and if we don't, it means this destination hasn't been setup on app.segment.com,
         // which in turn ALSO means that we shouldn't be sending events to it.
-        
-        
-        // apply .before and .enrichment types first ...
-        let beforeResult = timeline.applyPlugins(type: .before, event: incomingEvent)
-        let enrichmentResult = timeline.applyPlugins(type: .enrichment, event: beforeResult)
-        
-        // now we execute any overrides we may have made.  basically, the idea is to take an
-        // incoming event, like identify, and map it to whatever is appropriate for this destination.
-        var destinationResult: E? = nil
-        switch enrichmentResult {
-            case let e as IdentifyEvent:
-                destinationResult = identify(event: e) as? E
-            case let e as TrackEvent:
-                destinationResult = track(event: e) as? E
-            case let e as ScreenEvent:
-                destinationResult = screen(event: e) as? E
-            case let e as GroupEvent:
-                destinationResult = group(event: e) as? E
-            case let e as AliasEvent:
-                destinationResult = alias(event: e) as? E
-            default:
-                break
+
+        if let enabled = analytics?.settings()?.isDestinationEnabled(key: self.key), enabled == true {
+            // apply .before and .enrichment types first ...
+            let beforeResult = timeline.applyPlugins(type: .before, event: incomingEvent)
+            let enrichmentResult = timeline.applyPlugins(type: .enrichment, event: beforeResult)
+            
+            // now we execute any overrides we may have made.  basically, the idea is to take an
+            // incoming event, like identify, and map it to whatever is appropriate for this destination.
+            var destinationResult: E? = nil
+            switch enrichmentResult {
+                case let e as IdentifyEvent:
+                    destinationResult = identify(event: e) as? E
+                case let e as TrackEvent:
+                    destinationResult = track(event: e) as? E
+                case let e as ScreenEvent:
+                    destinationResult = screen(event: e) as? E
+                case let e as GroupEvent:
+                    destinationResult = group(event: e) as? E
+                case let e as AliasEvent:
+                    destinationResult = alias(event: e) as? E
+                default:
+                    break
+            }
+            
+            // apply .after plugins ...
+            result = timeline.applyPlugins(type: .after, event: destinationResult)
         }
 
-        // apply .after plugins ...
-        let afterResult = timeline.applyPlugins(type: .after, event: destinationResult)
-
-        return afterResult
+        return result
     }
 }
 

Tests/Segment-Tests/Analytics_Tests.swift

@@ -49,6 +49,59 @@ final class Analytics_Tests: XCTestCase {
 
         wait(for: [expectation], timeout: 1.0)
     }
+
+    func testDestinationEnabled() {
+        // need to clear settings for this one.
+        UserDefaults.standard.removePersistentDomain(forName: "com.segment.storage.test")
+        
+        let expectation = XCTestExpectation(description: "MyDestination Expectation")
+        let myDestination = MyDestination {
+            expectation.fulfill()
+        }
+
+        var settings = Settings(writeKey: "test")
+        if let existing = settings.integrations?.dictionaryValue {
+            var newIntegrations = existing
+            newIntegrations[myDestination.key] = true
+            settings.integrations = try! JSON(newIntegrations)
+        }
+        let configuration = Configuration(writeKey: "test")
+        configuration.defaultSettings(settings)
+        let analytics = Analytics(configuration: configuration)
+
+        analytics.add(plugin: myDestination)
+        
+        waitUntilStarted(analytics: analytics)
+        
+        analytics.track(name: "testDestinationEnabled")
+        
+        wait(for: [expectation], timeout: 1.0)
+    }
+    
+    // Linux doesn't support XCTExpectFailure
+    #if !os(Linux)
+    func testDestinationNotEnabled() {
+        // need to clear settings for this one.
+        UserDefaults.standard.removePersistentDomain(forName: "com.segment.storage.test")
+        
+        let expectation = XCTestExpectation(description: "MyDestination Expectation")
+        let myDestination = MyDestination {
+            expectation.fulfill()
+        }
+
+        let configuration = Configuration(writeKey: "test")
+        let analytics = Analytics(configuration: configuration)
+
+        analytics.add(plugin: myDestination)
+        
+        waitUntilStarted(analytics: analytics)
+        
+        analytics.track(name: "testDestinationEnabled")
+        
+        XCTExpectFailure()
+        wait(for: [expectation], timeout: 1.0)
+    }
+    #endif
 
     func testAnonymousId() {
         let analytics = Analytics(configuration: Configuration(writeKey: "test"))

Tests/Segment-Tests/Support/TestUtilities.swift

@@ -73,17 +73,25 @@ class MyDestination: DestinationPlugin {
     let type: PluginType
     let key: String
     var analytics: Analytics?
+    let trackCompletion: (() -> Void)?
 
-    init() {
+    init(trackCompletion: (() -> Void)? = nil) {
         self.key = "MyDestination"
         self.type = .destination
         self.timeline = Timeline()
+        self.trackCompletion = trackCompletion
     }
 
     func update(settings: Settings) {
         //
     }
 
+    func track(event: TrackEvent) -> TrackEvent? {
+        if let completion = trackCompletion {
+            completion()
+        }
+        return event
+    }
 }
 
 class OutputReaderPlugin: Plugin {