1 files changed, 69 insertions, 0 deletions
diff --git a/HutchTests/TicketDetailViewModelTests.swift b/HutchTests/TicketDetailViewModelTests.swift
index bf0bc60..ba4a476 100644
--- a/HutchTests/TicketDetailViewModelTests.swift
+++ b/HutchTests/TicketDetailViewModelTests.swift
@@ -27,4 +27,73 @@ struct TicketDetailViewModelTests {
         #expect(input["status"] as? String == TicketStatus.resolved.rawValue)
         #expect(input["resolution"] as? String == TicketResolution.fixed.rawValue)
     }
+
+    @Test
+    @MainActor
+    func ticketUpdateInputOmitsUnchangedFields() {
+        let input = TicketDetailViewModel.ticketUpdateInput(
+            subject: "Same subject",
+            body: "Same body",
+            currentSubject: "Same subject",
+            currentBody: "Same body"
+        )
+
+        #expect(input.isEmpty)
+    }
+
+    @Test
+    @MainActor
+    func ticketUpdateInputCarriesOnlyTheChangedField() {
+        let input = TicketDetailViewModel.ticketUpdateInput(
+            subject: "New subject",
+            body: "Same body",
+            currentSubject: "Old subject",
+            currentBody: "Same body"
+        )
+
+        #expect(input["subject"] as? String == "New subject")
+        #expect(!input.keys.contains("body"))
+    }
+
+    @Test
+    @MainActor
+    func ticketUpdateInputTrimsWhitespaceBeforeComparing() {
+        let input = TicketDetailViewModel.ticketUpdateInput(
+            subject: "  Same subject  ",
+            body: "\n Same body \n",
+            currentSubject: "Same subject",
+            currentBody: "Same body"
+        )
+
+        #expect(input.isEmpty)
+    }
+
+    @Test
+    @MainActor
+    func ticketUpdateInputUsesNilToClearBody() {
+        let input = TicketDetailViewModel.ticketUpdateInput(
+            subject: "Same subject",
+            body: "   ",
+            currentSubject: "Same subject",
+            currentBody: "Existing body"
+        )
+
+        // The key must survive with a nil value so it encodes as a JSON null and
+        // actually clears the body, rather than being dropped from the mutation.
+        #expect(input.keys.contains("body"))
+        #expect(input["body"] as? String == nil)
+    }
+
+    @Test
+    @MainActor
+    func ticketUpdateInputTreatsNilBodyAsEmpty() {
+        let input = TicketDetailViewModel.ticketUpdateInput(
+            subject: "Same subject",
+            body: "",
+            currentSubject: "Same subject",
+            currentBody: nil
+        )
+
+        #expect(input.isEmpty)
+    }
 }