标签：#postmanapi

Here's a bug your test suite probably wouldn't catch. A backend developer refactors the user model. The id field — an integer since forever — starts coming back as a string: "42" instead of 42 . Every value is still "correct". Your assertion pm.expect(user.id).to.eql(42) fails, sure — but only on the one endpoint you asserted id on, not the other nine that return users. Meanwhile three client apps that did user.id + 1 are now computing "421" . That's structural drift , and it's what actually breaks API consumers: renamed fields, changed types, properties that quietly vanish. Field-by-field value assertions catch it patchily and by accident. Schema validation catches it systematically — and in Postman it costs about ten lines, because the ajv JSON-schema validator is built into the script sandbox. The ten lines In Scripts → Post-response on any request that returns a user: const userSchema = { type : " object " , required : [ " id " , " name " , " email " ], properties : { id : { type : " integer " }, name : { type : " string " }, email : { type : " string " , pattern : " @ " } } }; pm . test ( " Response matches the user schema " , () => { pm . expect ( pm . response . json ()). to . be . jsonSchema ( userSchema ); }); That single test now fails if id becomes a string, if email disappears, if name becomes an object — every structural mutation, whether or not you thought to assert on that field's value. For an endpoint returning an array of users: const userListSchema = { type : " array " , minItems : 1 , items : userSchema // reuse the object schema }; pm . test ( " List matches schema " , () => { pm . expect ( pm . response . json ()). to . be . jsonSchema ( userListSchema ); }); Share one schema across every endpoint The real power move: your API returns users from /users , /users/:id , /login , /teams/:id/members … and they should all be the same shape . Store the schema once as a collection variable (JSON, stringified), and every request validates against the sa