add tests

Author: cherylEnkidu

Firestore/Swift/Source/Helper/PipelineHelper.swift

@@ -13,11 +13,17 @@
 // limitations under the License.
 
 enum Helper {
-  
-  enum HelperError: Error {
+  enum HelperError: Error, LocalizedError {
     case duplicateAlias(String)
+
+    public var errorDescription: String? {
+      switch self {
+      case let .duplicateAlias(message):
+        return message
+      }
+    }
   }
-  
+
   static func sendableToExpr(_ value: Sendable?) -> Expression {
     guard let value = value else {
       return Constant.nil
@@ -39,14 +45,14 @@ enum Helper {
   static func selectablesToMap(selectables: [Selectable]) -> ([String: Expression], Error?) {
     var exprMap = [String: Expression]()
     for selectable in selectables {
-        guard let value = selectable as? SelectableWrapper else {
-            fatalError("Selectable class must conform to SelectableWrapper.")
-        }
-        let alias = value.alias
-        if exprMap.keys.contains(alias) {
-            return ([:], HelperError.duplicateAlias("Duplicate alias '\(alias)' found in selectables."))
-        }
-        exprMap[alias] = value.expr
+      guard let value = selectable as? SelectableWrapper else {
+        fatalError("Selectable class must conform to SelectableWrapper.")
+      }
+      let alias = value.alias
+      if exprMap.keys.contains(alias) {
+        return ([:], HelperError.duplicateAlias("Duplicate alias '\(alias)' found in selectables."))
+      }
+      exprMap[alias] = value.expr
     }
     return (exprMap, nil)
   }
@@ -55,11 +61,14 @@ enum Helper {
     -> ([String: AggregateFunction], Error?) {
     var accumulatorMap = [String: AggregateFunction]()
     for aliasedAggregate in accumulators {
-        let alias = aliasedAggregate.alias
-        if accumulatorMap.keys.contains(alias) {
-            return ([:], HelperError.duplicateAlias("Duplicate alias '\(alias)' found in accumulators."))
-        }
-        accumulatorMap[alias] = aliasedAggregate.aggregate
+      let alias = aliasedAggregate.alias
+      if accumulatorMap.keys.contains(alias) {
+        return (
+          [:],
+          HelperError.duplicateAlias("Duplicate alias '\(alias)' found in accumulators.")
+        )
+      }
+      accumulatorMap[alias] = aliasedAggregate.aggregate
     }
     return (accumulatorMap, nil)
   }

Firestore/Swift/Source/Stages.swift

@@ -30,9 +30,9 @@ protocol Stage {
 }
 
 extension Stage {
-    var errorMessage: String? {
-        return nil
-    }
+  var errorMessage: String? {
+    return nil
+  }
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
@@ -160,12 +160,12 @@ class AddFields: Stage {
     self.selectables = selectables
     let (map, error) = Helper.selectablesToMap(selectables: selectables)
     if let error = error {
-        self.errorMessage = error.localizedDescription
-        self.bridge = AddFieldsStageBridge(fields: [:])
+      errorMessage = error.localizedDescription
+      bridge = AddFieldsStageBridge(fields: [:])
     } else {
-        self.errorMessage = nil
-        let objcAccumulators = map.mapValues { $0.toBridge() }
-        self.bridge = AddFieldsStageBridge(fields: objcAccumulators)
+      errorMessage = nil
+      let objcAccumulators = map.mapValues { $0.toBridge() }
+      bridge = AddFieldsStageBridge(fields: objcAccumulators)
     }
   }
 }
@@ -196,12 +196,12 @@ class Select: Stage {
   init(selections: [Selectable]) {
     let (map, error) = Helper.selectablesToMap(selectables: selections)
     if let error = error {
-        self.errorMessage = error.localizedDescription
-        self.bridge = SelectStageBridge(selections: [:])
+      errorMessage = error.localizedDescription
+      bridge = SelectStageBridge(selections: [:])
     } else {
-        self.errorMessage = nil
-        let objcSelections = map.mapValues { Helper.sendableToExpr($0).toBridge() }
-        self.bridge = SelectStageBridge(selections: objcSelections)
+      errorMessage = nil
+      let objcSelections = map.mapValues { Helper.sendableToExpr($0).toBridge() }
+      bridge = SelectStageBridge(selections: objcSelections)
     }
   }
 }
@@ -215,12 +215,12 @@ class Distinct: Stage {
   init(groups: [Selectable]) {
     let (map, error) = Helper.selectablesToMap(selectables: groups)
     if let error = error {
-        self.errorMessage = error.localizedDescription
-        self.bridge = DistinctStageBridge(groups: [:])
+      errorMessage = error.localizedDescription
+      bridge = DistinctStageBridge(groups: [:])
     } else {
-        self.errorMessage = nil
-        let objcGroups = map.mapValues { Helper.sendableToExpr($0).toBridge() }
-        self.bridge = DistinctStageBridge(groups: objcGroups)
+      errorMessage = nil
+      let objcGroups = map.mapValues { Helper.sendableToExpr($0).toBridge() }
+      bridge = DistinctStageBridge(groups: objcGroups)
     }
   }
 }
@@ -237,23 +237,23 @@ class Aggregate: Stage {
     self.accumulators = accumulators
 
     if let groups = groups {
-        let (map, error) = Helper.selectablesToMap(selectables: groups)
-        if let error = error {
-            self.errorMessage = error.localizedDescription
-            self.bridge = AggregateStageBridge(accumulators: [:], groups: [:])
-            return
-        }
-        self.groups = map
+      let (map, error) = Helper.selectablesToMap(selectables: groups)
+      if let error = error {
+        errorMessage = error.localizedDescription
+        bridge = AggregateStageBridge(accumulators: [:], groups: [:])
+        return
+      }
+      self.groups = map
     }
 
     let (accumulatorsMap, error) = Helper.aliasedAggregatesToMap(accumulators: accumulators)
     if let error = error {
-        self.errorMessage = error.localizedDescription
-        self.bridge = AggregateStageBridge(accumulators: [:], groups: [:])
-        return
+      errorMessage = error.localizedDescription
+      bridge = AggregateStageBridge(accumulators: [:], groups: [:])
+      return
     }
-    
-    self.errorMessage = nil
+
+    errorMessage = nil
     let accumulatorBridgesMap = accumulatorsMap.mapValues { $0.bridge }
     bridge = AggregateStageBridge(
       accumulators: accumulatorBridgesMap,