internal: extract tests into own module

test/create-stub-instance-test.js

@@ -0,0 +1,158 @@
+"use strict";
+
+var referee = require("@sinonjs/referee");
+var createStub = require("../lib/sinon/stub");
+var createStubInstance = require("../lib/sinon/create-stub-instance")
+var assert = referee.assert;
+var refute = referee.refute;
+
+describe("createStubInstance", function () {
+    it("stubs existing methods", function () {
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        var stub = createStubInstance(Class);
+        stub.method.returns(3);
+        assert.equals(3, stub.method());
+    });
+
+    it("throws with no methods to stub", function () {
+        var Class = function () {
+            return;
+        };
+
+        assert.exception(
+            function () {
+                createStubInstance(Class);
+            },
+            {
+                message:
+                    "Found no methods on object to which we could apply mutations",
+            }
+        );
+    });
+
+    it("doesn't call the constructor", function () {
+        var Class = function (a, b) {
+            var c = a + b;
+            throw c;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        var stub = createStubInstance(Class);
+        refute.exception(function () {
+            stub.method(3);
+        });
+    });
+
+    it("retains non function values", function () {
+        var TYPE = "some-value";
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+        Class.prototype.type = TYPE;
+
+        var stub = createStubInstance(Class);
+        assert.equals(TYPE, stub.type);
+    });
+
+    it("has no side effects on the prototype", function () {
+        var proto = {
+            method: function () {
+                throw new Error("error");
+            },
+        };
+        var Class = function () {
+            return;
+        };
+        Class.prototype = proto;
+
+        var stub = createStubInstance(Class);
+        refute.exception(stub.method);
+        assert.exception(proto.method);
+    });
+
+    it("throws exception for non function params", function () {
+        var types = [{}, 3, "hi!"];
+
+        for (var i = 0; i < types.length; i++) {
+            // yes, it's silly to create functions in a loop, it's also a test
+            // eslint-disable-next-line no-loop-func
+            assert.exception(function () {
+                createStubInstance(types[i]);
+            });
+        }
+    });
+
+    it("allows providing optional overrides", function () {
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        var stub = createStubInstance(Class, {
+            method: createStub().returns(3),
+        });
+
+        assert.equals(3, stub.method());
+    });
+
+    it("allows providing optional returned values", function () {
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        var stub = createStubInstance(Class, {
+            method: 3,
+        });
+
+        assert.equals(3, stub.method());
+    });
+
+    it("allows providing null as a return value", function () {
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        var stub = createStubInstance(Class, {
+            method: null,
+        });
+
+        assert.equals(null, stub.method());
+    });
+
+    it("throws an exception when trying to override non-existing property", function () {
+        var Class = function () {
+            return;
+        };
+        Class.prototype.method = function () {
+            return;
+        };
+
+        assert.exception(
+            function () {
+                createStubInstance(Class, {
+                    foo: createStub().returns(3),
+                });
+            },
+            { message: "Cannot stub foo. Property does not exist!" }
+        );
+    });
+})