How to create unit tests for in-memory data storage?

php editor Xiaoxin will introduce you how to create unit tests for memory data storage. During the development process, unit testing is one of the important means to ensure code quality and functional correctness. For memory data storage, we can use testing frameworks such as PHPUnit to write corresponding test cases. First, we need to create a test class and then write the relevant test logic in the test method. In each test method, we can use assertions to verify that the expected results match the actual results. Through such unit testing, we can discover and fix potential problems in time and improve the stability and reliability of the code.

Question content

I want to create some simple rest api. I decided to create my own in-memory data store to implement such an interface:

type datastore interface {
    add(*element) error
    get(elementid) (*element, error)
    update(*element) error
    delete(elementid) error
    getall() []*element
}

type datastore struct {
    mu     sync.mutex
    bucket map[string]*element
}

func newdb() *datastore {
    return &datastore {
        bucket: make(map[string]*element),
    }
}

How should it be unit tested?

Some of the tests I managed to create look like this:

func testgetalltodotasks(t *testing.t) {
    ts := newdb()
    var elem = &element{fielda : "a" , fieldb : "b"}
    ts.create(elem)

    want := []*element{elem}

    if got := ts.getall(); !reflect.deepequal(got, want) {
        t.errorf("got %v wanted %v", got, want)
    }
}

But when I want to test other methods (such as update), I realize that I need to use create first and then update, like this:

func TestUpdateTODOTasks(t *testing.T) {
    ts := NewDB()
    var elem = &Element{fieldA : "A" , fieldB : "B"}
    ts.Create(elem)
    if err != nil {
        t.Errorf("=> failed to create: %v", err.Error())
    }
    var updated_elem = &Element{fieldA : "A-updated" , fieldB : "B"}

    err = ts.Update(updated_elem )

    if err != nil {
        t.Errorf("=> failed to update: %v", err.Error())
    }

}

Workaround

You can initialize the underlying mapping based on the implementation details that the storage actually uses the mapping behind the scenes.

In general, you can really benefit from testing like you describe. Therefore, use the defined API to seed the storage for testing. It brings your tests closer to how customers use your code. No need to manually modify the underlying state. I've seen a lot of tests done this way, but they usually become unmaintainable and unstable.

Don't get too hung up on the fact that a unit test must check a function. In fact, they're more about testing complete, self-contained small parts of the software, so it doesn't have to be a single feature at all.

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