Add tests

Sources/SwiftGraph/GraphTraverser.swift

@@ -41,9 +41,11 @@ protocol GraphTraverser {
     ///   - initalVertexIndex: The index of the initial vertex
     ///   - goalTest: Returns true if a given vertex index is a goal. When this closure returns true
     ///               The algorithm stops traversing the graph when this closure returns true.
+    ///               The initial vertex is checked against the closure too.
     ///   - reducer: A reducer that is fed with each visited vertex. The input parameter
     ///              is the edge from the previous vertex to the visited vertex.
     ///              If the return value is false, the neighbours of the input vertex will not be visited.
+    ///              The initialVertex is not fed to the reducer.
     /// - Returns: The index of the first vertex found to satisfy goalTest or nil if no vertex is found.
     func from(_ initalVertexIndex: Int, goalTest: (Int) -> Bool, reducer: G.Reducer) -> Int?
 }

Tests/SwiftGraphTests/SwiftGraphSearchTests.swift

@@ -225,6 +225,29 @@ class SwiftGraphSearchTests: XCTestCase {
         XCTAssertTrue(atLeastOnePathHasLenght2, "In a Complete Graph, the dfs must visit all nodes in the same path")
     }
 
+    func testDfsInCompleteGraphWithGoalTestByIndex() {
+        var visited = Array<Bool>.init(repeating: false, count: 200)
+        let graph = CompleteGraph.build(withVertices: Array(0...199))
+        _ = graph.dfs(fromIndex: 0, goalTest: { i in
+            visited[i] = true
+            return false
+        })
+        let numVisitedVertices = visited.filter({ $0 }).count
+        XCTAssertEqual(numVisitedVertices, 200, "The DFS must visit all the vertices")
+    }
+
+    func testDfsGoalTestOnInitialVertex() {
+        var visited = false
+        let graph = CompleteGraph.build(withVertices: Array(0...3))
+        _ = graph.dfs(fromIndex: 0, goalTest: { i in
+            if (i == 0) {
+                visited = true
+            }
+            return true
+        })
+        XCTAssertTrue(visited, "The DFS must check if the initialVertex is already a goal.")
+    }
+
     func testBFS1() {
         // Seattle -> Miami
         let result = cityGraph.bfs(from: "Seattle", to: "Miami")
@@ -359,6 +382,29 @@ class SwiftGraphSearchTests: XCTestCase {
         let allPathsHavLenght1 = paths.allSatisfy { $0.count == 1 }
         XCTAssertTrue(allPathsHavLenght1, "In a Triangle Graph, the bfs must visit all nodes directly.")
     }
+
+    func testBfsInCompleteGraphWithGoalTestByIndex() {
+        var visited = Array<Bool>.init(repeating: false, count: 200)
+        let graph = CompleteGraph.build(withVertices: Array(0...199))
+        _ = graph.bfs(fromIndex: 0, goalTest: { i in
+            visited[i] = true
+            return false
+        })
+        let numVisitedVertices = visited.filter({ $0 }).count
+        XCTAssertEqual(numVisitedVertices, 200, "The BFS must visit all the vertices")
+    }
+
+    func testBfsGoalTestOnInitialVertex() {
+        var visited = false
+        let graph = CompleteGraph.build(withVertices: Array(0...3))
+        _ = graph.bfs(fromIndex: 0, goalTest: { i in
+            if (i == 0) {
+                visited = true
+            }
+            return true
+        })
+        XCTAssertTrue(visited, "The BFS must check if the initialVertex is already a goal.")
+    }
 
     func testFindAll() {
         // New York -> all cities starting with "S"