#1 3.1 Three in One: test for Peek method

ch03/01_threesome_test.go

@@ -123,7 +123,52 @@ func TestNthPush(t *testing.T) {
 }
 
 func TestNthPeek(t *testing.T) {
-	// TBD
+	n, m := 3, 2
+	nth := new(NthStack)
+
+	nth.n = n
+	nth.storage = make([]int, n*(m+1))
+	nth.start = make([]int, n)
+	nth.len = make([]int, n)
+	nth.cap = make([]int, n)
+
+	values := [][]int{
+		{10, 1},
+		{20, 2},
+		{30, 3},
+	}
+
+	for i := 0; i < n; i++ {
+		start := i * (m + 1)
+		stop := start + m
+
+		nth.start[i] = start
+		nth.len[i] = 0
+		nth.cap[i] = 1
+
+		for j := start; j < stop; j++ {
+			nth.storage[j] = values[i][j-start]
+			nth.len[i]++
+			nth.cap[i]++
+		}
+	}
+
+	for i := 0; i < nth.n; i++ {
+		for j := 0; nth.len[i] > 0; j++ {
+			val := values[i][j]
+
+			num, err := nth.Peek(i)
+			if err != nil {
+				t.Errorf("%dth stack, %dth Peek() expected to be valid, got error %s\n", (i + 1), (j + 1), err)
+			}
+
+			if num != val {
+				t.Errorf("%dth stack, %dth Peek() expected to be %d, got %d\n", (i + 1), (j + 1), val, num)
+			}
+
+			nth.len[i]--
+		}
+	}
 }
 
 func TestNthIsEmpty(t *testing.T) {