add IsType.

Author: h12w

DESIGN.md

@@ -320,14 +320,14 @@ This is a complete list of expectations, "+" means already supported:
 * +Panic: panic and panic with an object
 * +Equal: deep equal
 *  Is: shallow equal
+* +IsType: if a interface is of a type
 *  Order comparision: >, <, >=, <=, Within(delta).Of(value)
 *  Composition: Not, And, Or
 *  True/False: can be supported by Is(true), Is(false)
 *  Nil: can be supported by Is(nil)
 *  Empty: empty for container types
 *  Error: can be supported by Equal
 *  Implements: can be supported by IsType
-*  IsType: if a interface is of a type
 *  String
     - +HasPrefix
     - +HasSuffix

expectation/checker.go

@@ -49,6 +49,13 @@ func Panic(actual, expected interface{}, skip int) (ret error) {
 	return nil
 }
 
+func IsType(actual, expected interface{}, skip int) error {
+	if reflect.TypeOf(actual) != reflect.TypeOf(expected) {
+		return errors.Compare(actual, expected, "to have type of", skip+1)
+	}
+	return nil
+}
+
 // Equal is the fluent method for checker Equal.
 func (a *Actual) Equal(expected interface{}) {
 	a.to(Equal, expected, 1)
@@ -63,3 +70,8 @@ func (a *Actual) NotEqual(expected interface{}) {
 func (a *Actual) Panic() {
 	a.to(Panic, nil, 1)
 }
+
+// IsType is the fluent method for checker IsType.
+func (a *Actual) IsType(expected interface{}) {
+	a.to(IsType, expected, 1)
+}

expectation/checker_test.go

@@ -53,3 +53,12 @@ var panicTestCases = []expectTestCase{
 func TestPanic(t *testing.T) {
 	testExpectations(t, panicTestCases)
 }
+
+var isTypeTestCases = []expectTestCase{
+	{`expect(int(0)).IsType(int(1))`, func(expect ExpectFunc) { expect(int(0)).IsType(int(1)) }, true},
+	{`expect(int(0)).IsType(bool(true))`, func(expect ExpectFunc) { expect(int(0)).IsType(bool(true)) }, false},
+}
+
+func TestIsType(t *testing.T) {
+	testExpectations(t, isTypeTestCases)
+}