Fixing decoding times if times was never encoded error (#12)

# [*Fixing Decoding Times
Error*](#12 (comment))

## ⚙️ Release Notes 
- This PR changes the decoding schedule, so it only decodes the times
field if it is present. This is necessary because times is not encoded
if it was empty, so then it errors when trying to decode it if it was
never encoded.

## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

Sources/SpeziMedication/Models/Schedule.swift

@@ -38,7 +38,7 @@ public struct Schedule: Codable, Equatable, Hashable {
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
         self.frequency = try container.decode(Frequency.self, forKey: .frequency)
-        self.times = try container.decode([ScheduledTime].self, forKey: .times)
+        self.times = try container.decodeIfPresent([ScheduledTime].self, forKey: .times) ?? []
         self.startDate = try container.decode(Date.self, forKey: .startDate)
     }
 

Tests/SpeziMedicationTests/SpeziMedicationTests.swift

@@ -11,6 +11,59 @@ import XCTest
 
 
 final class SpeziMedicationTests: XCTestCase {
+    func testScheduleDecodingWithAndWithoutTimes() throws {
+        let jsonDecoder = JSONDecoder()
+        jsonDecoder.dateDecodingStrategy = .iso8601
+
+        // Test decoding without times
+        let noTimesJSON = """
+        {
+            "frequency": {
+                "asNeeded": true
+            },
+            "startDate": "2023-12-07T08:00:00Z"
+        }
+        """
+        guard let data = noTimesJSON.data(using: .utf8) else {
+            XCTFail("Failed to encode JSON string to Data")
+            return
+        }
+        let noTimesSchedule = try jsonDecoder.decode(Schedule.self, from: data)
+        XCTAssertEqual(noTimesSchedule.times, [])
+
+        // Test decoding with times
+        let withTimesJSON = """
+        {
+            "frequency": {
+                "regularDayIntervals": 2
+            },
+            "startDate": "2023-12-07T08:00:00Z",
+            "times": [
+                {
+                    "time": {
+                        "hour": 8,
+                        "minute": 0
+                    },
+                    "dosage": 5.0
+                },
+                {
+                    "time": {
+                        "hour": 15,
+                        "minute": 0
+                    },
+                    "dosage": 5.0
+                }
+            ]
+        }
+        """
+        guard let dataWithTimes = withTimesJSON.data(using: .utf8) else {
+            XCTFail("Failed to encode JSON string to Data")
+            return
+        }
+        let withTimesSchedule = try jsonDecoder.decode(Schedule.self, from: dataWithTimes)
+        XCTAssertNotNil(withTimesSchedule.times)
+    }
+
     // swiftlint:disable:next function_body_length
     func testScheduleEncoding() throws {
         let jsonEncoder = JSONEncoder()