transform wasn't correctly enforcing invariants

.gitignore

@@ -2,3 +2,4 @@
 /.build
 /Packages
 /Carthage
+/.swiftpm

Rearrange/RangeMutation.swift

@@ -44,6 +44,10 @@ public struct RangeMutation {
 
 extension RangeMutation {
     public func transform(location: Int) -> Int? {
+        if let l = presetLimit {
+            precondition(location <= l)
+        }
+
         if range.location > location {
             return location
         }
@@ -54,19 +58,19 @@ extension RangeMutation {
             return location
         }
 
-        if range.max <= location {
-            let result = location + delta
+        if range.max > location {
+            return nil
+        }
 
-            precondition(result >= 0)
+        let result = location + delta
 
-            if let l = presetLimit {
-                precondition(result <= l)
-            }
+        precondition(result >= 0)
 
-            return result
+        if presetLimit != nil {
+            precondition(result <= postApplyLimit)
         }
 
-        return nil
+        return result
     }
 }
 

Rearrange/Rearrange.xcconfig

@@ -14,8 +14,8 @@
 PRODUCT_NAME = Rearrange
 PRODUCT_BUNDLE_IDENTIFIER = com.chimehq.Rearrange
 PRODUCT_MODULE_NAME = Rearrange
-CURRENT_PROJECT_VERSION = 5
-MARKETING_VERSION = 1.1.2
+CURRENT_PROJECT_VERSION = 6
+MARKETING_VERSION = 1.1.3
 
 INFOPLIST_FILE = Rearrange/Info.plist
 MACH_O_TYPE = staticlib

RearrangeTests/RangeMutationTests.swift

@@ -23,6 +23,12 @@ class RangeMutationTests: XCTestCase {
         XCTAssertEqual(change.transform(location: 14), 15)
     }
 
+    func testMutationAtLimitLocation() {
+        let change = RangeMutation(range: NSRange(5..<5), delta: 1, limit: 5)
+
+        XCTAssertEqual(change.transform(location: 5), 6)
+    }
+
     func testMutationAfterLocation() {
         let change = RangeMutation(range: NSMakeRange(11, 1), delta: 1, limit: 15)
 
@@ -111,7 +117,7 @@ class RangeMutationTests: XCTestCase {
     }
 
     func testMutationAtBeginning() {
-        let change = RangeMutation(range: NSMakeRange(5, 1), delta: -1, limit: 11)
+        let change = RangeMutation(range: NSMakeRange(5, 1), delta: -1, limit: 12)
 
         XCTAssertEqual(change.transform(range: NSMakeRange(10, 2)), NSMakeRange(9, 2))
     }
@@ -123,7 +129,7 @@ class RangeMutationTests: XCTestCase {
     }
 
     func testMutationDecreasesLengthOfRange() {
-        let change = RangeMutation(range: NSMakeRange(5, 1), delta: -1, limit: 9)
+        let change = RangeMutation(range: NSMakeRange(5, 1), delta: -1, limit: 10)
 
         XCTAssertEqual(change.transform(range: NSMakeRange(0, 10)), NSMakeRange(0, 9))
     }