【SC随笔】Java测试mutator方法的注意点

 /** * Add, change, or remove a weighted directed edge in this graph. * If weight is nonzero, add an edge or update the weight of that edge; * vertices with the given labels are added to the graph if they do not * already exi * s zero, remove the edge if it exists (the graph is not * otherwise modified). * * @param source label of the source vertex * @param target label of the target vertex * @param weight nonnegative weight of the edge * @return the previous weight of the edge, or zero if there was no such * edge */
    public int set(L source, L target, int weight);

    @Test
public void testSet(){ 

Graph<String> instance = emptyInstance();
assertEquals("add a edge that doesn't exist before",
0, instance.set("v1","v2",1));
assertEquals("add a edge that doesn't exist before",
0, instance.set("v1","v3",2));
assertEquals("add a edge that doesn't exist before",
0, instance.set("v2","v3",3));
assertEquals("add a edge that does exist before",
1, instance.set("v1","v2",5));
assertEquals("remove a edge",
5, instance.set("v1","v2",0));
assertEquals("add a edge the source and target of it didn't exist",
0, instance.set("v4","v5",1));
}

 @Test
public void testSet(){ 

Graph<String> instance = emptyInstance();
assertEquals("add a edge that doesn't exist before",
0, instance.set("v1","v2",1));
Map<String,Integer> expect = new HashMap<>();
expect.put("v2",1);
assertEquals(expect,instance.targets("v1"));
assertEquals("add a edge that doesn't exist before",
0, instance.set("v1","v3",2));
expect.put("v3",2);
assertEquals(expect,instance.targets("v1"));
assertEquals("add a edge that doesn't exist before",
0, instance.set("v2","v3",3));
Map<String,Integer> expect2 = new HashMap<>();
expect2.put("v1",2);
expect2.put("v2",3);
assertEquals(expect2,instance.sources("v3"));
assertEquals("add a edge that does exist before",
1, instance.set("v1","v2",5));
expect.put("v2",5);
assertEquals(expect,instance.targets("v1"));
assertEquals("remove a edge",
5, instance.set("v1","v2",0));
expect.remove("v2");
assertEquals(expect,instance.targets("v1"));
assertEquals("add a edge the source and target of it didn't exist",
0, instance.set("v4","v5",1));
Map<String,Integer> expect3 = new HashMap<>();
expect3.put("v5",1);
assertEquals(expect3,instance.targets("v4"));
Map<String,Integer> expect4 = new HashMap<>();
expect4.put("v4",1);
assertEquals(expect4,instance.sources("v5"));
}