WIP: documentation and unit tests

CoreStoreTests/MigrationChainTests.swift

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+//
+//  MigrationChainTests.swift
+//  CoreStore
+//
+//  Copyright © 2016 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import XCTest
+
+@testable
+import CoreStore
+
+class MigrationChainTests: XCTestCase {
+    
+    @objc dynamic func testEmptyChain() {
+        
+        let chain: MigrationChain = nil
+        expect(chain.valid).to(beTrue())
+        expect(chain.empty).to(beTrue())
+        
+        expect(chain.contains("version1")).to(beFalse())
+        
+        expect(chain.nextVersionFrom("version1")).to(beNil())
+    }
+    
+    @objc dynamic func testSingleChain() {
+        
+        let chain: MigrationChain = "version1"
+        expect(chain.valid).to(beTrue())
+        expect(chain.empty).to(beTrue())
+        
+        expect(chain.contains("version1")).to(beTrue())
+        expect(chain.contains("version2")).to(beFalse())
+        
+        expect(chain.nextVersionFrom("version1")).to(beNil())
+        expect(chain.nextVersionFrom("version2")).to(beNil())
+    }
+    
+    @objc dynamic func testLinearChain() {
+        
+        let chain: MigrationChain = ["version1", "version2", "version3", "version4"]
+        expect(chain.valid).to(beTrue())
+        expect(chain.empty).to(beFalse())
+        
+        expect(chain.contains("version1")).to(beTrue())
+        expect(chain.contains("version2")).to(beTrue())
+        expect(chain.contains("version3")).to(beTrue())
+        expect(chain.contains("version4")).to(beTrue())
+        expect(chain.contains("version5")).to(beFalse())
+        
+        expect(chain.nextVersionFrom("version1")).to(equal("version2"))
+        expect(chain.nextVersionFrom("version2")).to(equal("version3"))
+        expect(chain.nextVersionFrom("version3")).to(equal("version4"))
+        expect(chain.nextVersionFrom("version4")).to(beNil())
+        expect(chain.nextVersionFrom("version5")).to(beNil())
+    }
+    
+    @objc dynamic func testTreeChain() {
+        
+        let chain: MigrationChain = [
+            "version1": "version4",
+            "version2": "version3",
+            "version3": "version4"
+        ]
+        expect(chain.valid).to(beTrue())
+        expect(chain.empty).to(beFalse())
+        
+        expect(chain.contains("version1")).to(beTrue())
+        expect(chain.contains("version2")).to(beTrue())
+        expect(chain.contains("version3")).to(beTrue())
+        expect(chain.contains("version4")).to(beTrue())
+        expect(chain.contains("version5")).to(beFalse())
+        
+        expect(chain.nextVersionFrom("version1")).to(equal("version4"))
+        expect(chain.nextVersionFrom("version2")).to(equal("version3"))
+        expect(chain.nextVersionFrom("version3")).to(equal("version4"))
+        expect(chain.nextVersionFrom("version4")).to(beNil())
+        expect(chain.nextVersionFrom("version5")).to(beNil())
+        
+        // The cases below will trigger assertion failures internally
+        
+        //        let linearLoopChain: MigrationChain = ["version1", "version2", "version1", "version3", "version4"]
+        //        XCTAssertFalse(linearLoopChain.valid, "linearLoopChain.valid")
+        //
+        //        let treeAmbiguousChain: MigrationChain = [
+        //            "version1": "version4",
+        //            "version2": "version3",
+        //            "version1": "version2",
+        //            "version3": "version4"
+        //        ]
+        //        XCTAssertFalse(treeAmbiguousChain.valid, "treeAmbiguousChain.valid")
+    }
+}