[#473] Add tests for rem values of traverser

Signed-off-by: Alex Vanin <a.vanin@yadro.com>

pkg/services/object_manager/placement/traverser_test.go

@@ -208,3 +208,55 @@ func TestTraverserObjectScenarios(t *testing.T) {
 		require.True(t, tr.Success())
 	})
 }
+
+func TestTraverserRemValues(t *testing.T) {
+	selectors := []int{3, 4, 5}
+	replicas := []int{2, 3, 4}
+
+	nodes, cnr := testPlacement(t, selectors, replicas)
+	nodesCopy := copyVectors(nodes)
+
+	testCases := [...]struct {
+		name        string
+		copyNumbers []uint32
+		expectedRem []int
+	}{
+		{
+			name:        "zero copy numbers",
+			copyNumbers: []uint32{},
+			expectedRem: replicas,
+		},
+		{
+			name:        "compatible zero copy numbers",
+			copyNumbers: []uint32{0},
+			expectedRem: replicas,
+		},
+		{
+			name:        "copy numbers for all replicas",
+			copyNumbers: []uint32{1, 1, 1},
+			expectedRem: []int{1, 1, 1},
+		},
+		{
+			name:        "single copy numbers for multiple replicas",
+			copyNumbers: []uint32{1},
+			expectedRem: []int{1}, // may be a bit unexpected
+		},
+		{
+			name:        "multiple copy numbers for multiple replicas",
+			copyNumbers: []uint32{1, 1},
+			expectedRem: []int{1, 1, 4},
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			tr, err := NewTraverser(
+				ForContainer(cnr),
+				UseBuilder(&testBuilder{vectors: nodesCopy}),
+				WithCopyNumbers(testCase.copyNumbers),
+			)
+			require.NoError(t, err)
+			require.Equal(t, testCase.expectedRem, tr.rem)
+		})
+	}
+}