feat: Support iter.Seqs in [Not]Contains and [Not]ElementsMatch

assert/assertions.go

@@ -530,7 +530,7 @@ func NotSame(t TestingT, expected, actual interface{}, msgAndArgs ...interface{}
 
 	same, ok := samePointers(expected, actual)
 	if !ok {
-		//fails when the arguments are not pointers
+		// fails when the arguments are not pointers
 		return !(Fail(t, "Both arguments must be pointers", msgAndArgs...))
 	}
 
@@ -549,7 +549,7 @@ func NotSame(t TestingT, expected, actual interface{}, msgAndArgs ...interface{}
 func samePointers(first, second interface{}) (same bool, ok bool) {
 	firstPtr, secondPtr := reflect.ValueOf(first), reflect.ValueOf(second)
 	if firstPtr.Kind() != reflect.Ptr || secondPtr.Kind() != reflect.Ptr {
-		return false, false //not both are pointers
+		return false, false // not both are pointers
 	}
 
 	firstType, secondType := reflect.TypeOf(first), reflect.TypeOf(second)
@@ -918,7 +918,7 @@ func containsElement(list interface{}, element interface{}) (ok, found bool) {
 
 }
 
-// Contains asserts that the specified string, list(array, slice...) or map contains the
+// Contains asserts that the specified string, list(array, slice, sequence...) or map contains the
 // specified substring or element.
 //
 //	assert.Contains(t, "Hello World", "World")
@@ -929,6 +929,7 @@ func Contains(t TestingT, s, contains interface{}, msgAndArgs ...interface{}) bo
 		h.Helper()
 	}
 
+	s = seqToSlice(s)
 	ok, found := containsElement(s, contains)
 	if !ok {
 		return Fail(t, fmt.Sprintf("%#v could not be applied builtin len()", s), msgAndArgs...)
@@ -952,6 +953,7 @@ func NotContains(t TestingT, s, contains interface{}, msgAndArgs ...interface{})
 		h.Helper()
 	}
 
+	s = seqToSlice(s)
 	ok, found := containsElement(s, contains)
 	if !ok {
 		return Fail(t, fmt.Sprintf("%#v could not be applied builtin len()", s), msgAndArgs...)
@@ -1088,6 +1090,10 @@ func ElementsMatch(t TestingT, listA, listB interface{}, msgAndArgs ...interface
 	if h, ok := t.(tHelper); ok {
 		h.Helper()
 	}
+	// Convert sequences to lists, if applicable
+	listA = seqToSlice(listA)
+	listB = seqToSlice(listB)
+
 	if isEmpty(listA) && isEmpty(listB) {
 		return true
 	}
@@ -1175,8 +1181,8 @@ func formatListDiff(listA, listB interface{}, extraA, extraB []interface{}) stri
 	return msg.String()
 }
 
-// NotElementsMatch asserts that the specified listA(array, slice...) is NOT equal to specified
-// listB(array, slice...) ignoring the order of the elements. If there are duplicate elements,
+// NotElementsMatch asserts that the specified listA(array, slice, sequence...) is NOT equal to specified
+// listB(array, slice, sequence...) ignoring the order of the elements. If there are duplicate elements,
 // the number of appearances of each of them in both lists should not match.
 // This is an inverse of ElementsMatch.
 //
@@ -1189,6 +1195,9 @@ func NotElementsMatch(t TestingT, listA, listB interface{}, msgAndArgs ...interf
 	if h, ok := t.(tHelper); ok {
 		h.Helper()
 	}
+	// Convert sequences to lists, if applicable
+	listA = seqToSlice(listA)
+	listB = seqToSlice(listB)
 	if isEmpty(listA) && isEmpty(listB) {
 		return Fail(t, "listA and listB contain the same elements", msgAndArgs)
 	}

assert/assertions_seq_test.go

@@ -0,0 +1,179 @@
+//go:build go1.23 || goexperiment.rangefunc
+
+package assert
+
+import (
+	"fmt"
+	"testing"
+)
+
+// go.mod version is set to 1.17, which precludes the use of generics (even though this file wouldn't be taken into
+// account per the build tags).
+
+func intSeq(s ...int) func(yield func(int) bool) {
+	return func(yield func(int) bool) {
+		for _, elem := range s {
+			if !yield(elem) {
+				break
+			}
+		}
+	}
+}
+
+func strSeq(s ...string) func(yield func(string) bool) {
+	return func(yield func(string) bool) {
+		for _, elem := range s {
+			if !yield(elem) {
+				break
+			}
+		}
+	}
+}
+
+func TestElementsMatch_Seq(t *testing.T) {
+	mockT := new(testing.T)
+
+	cases := []struct {
+		expected interface{}
+		actual   interface{}
+		result   bool
+	}{
+		{intSeq(), intSeq(), true},
+		{intSeq(1), intSeq(1), true},
+		{intSeq(1, 1), intSeq(1, 1), true},
+		{intSeq(1, 2), intSeq(1, 2), true},
+		{intSeq(1, 2), intSeq(2, 1), true},
+		{strSeq("hello", "world"), strSeq("world", "hello"), true},
+		{strSeq("hello", "hello"), strSeq("hello", "hello"), true},
+		{strSeq("hello", "hello", "world"), strSeq("hello", "world", "hello"), true},
+		{intSeq(), nil, true},
+
+		// not matching
+		{intSeq(1), intSeq(1, 1), false},
+		{intSeq(1, 2), intSeq(2, 2), false},
+		{strSeq("hello", "hello"), strSeq("hello"), false},
+	}
+
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("ElementsMatch(%#v, %#v)", seqToSlice(c.expected), seqToSlice(c.actual)), func(t *testing.T) {
+			res := ElementsMatch(mockT, c.actual, c.expected)
+
+			if res != c.result {
+				t.Errorf("ElementsMatch(%#v, %#v) should return %v", seqToSlice(c.actual), seqToSlice(c.expected), c.result)
+			}
+		})
+	}
+}
+
+func TestNotElementsMatch_Seq(t *testing.T) {
+	mockT := new(testing.T)
+
+	cases := []struct {
+		expected interface{}
+		actual   interface{}
+		result   bool
+	}{
+		// not matching
+		{intSeq(1), intSeq(), true},
+		{intSeq(), intSeq(2), true},
+		{intSeq(1), intSeq(2), true},
+		{intSeq(1), intSeq(1, 1), true},
+		{intSeq(1, 2), intSeq(3, 4), true},
+		{intSeq(3, 4), intSeq(1, 2), true},
+		{intSeq(1, 1, 2, 3), intSeq(1, 2, 3), true},
+		{strSeq("hello"), strSeq("world"), true},
+		{strSeq("hello", "hello"), strSeq("world", "world"), true},
+
+		// matching
+		{intSeq(), nil, false},
+		{intSeq(), intSeq(), false},
+		{intSeq(1), intSeq(1), false},
+		{intSeq(1, 1), intSeq(1, 1), false},
+		{intSeq(1, 2), intSeq(2, 1), false},
+		{intSeq(1, 1, 2), intSeq(1, 2, 1), false},
+		{strSeq("hello", "world"), strSeq("world", "hello"), false},
+		{strSeq("hello", "hello"), strSeq("hello", "hello"), false},
+		{strSeq("hello", "hello", "world"), strSeq("hello", "world", "hello"), false},
+	}
+
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("NotElementsMatch(%#v, %#v)", seqToSlice(c.expected), seqToSlice(c.actual)), func(t *testing.T) {
+			res := NotElementsMatch(mockT, c.actual, c.expected)
+
+			if res != c.result {
+				t.Errorf("NotElementsMatch(%#v, %#v) should return %v", seqToSlice(c.actual), seqToSlice(c.expected), c.result)
+			}
+		})
+	}
+}
+
+func TestContainsNotContains_Seq(t *testing.T) {
+
+	type A struct {
+		Name, Value string
+	}
+	complexSeq := func(s ...*A) func(yield func(*A) bool) {
+		return func(yield func(*A) bool) {
+			for _, elem := range s {
+				if !yield(elem) {
+					break
+				}
+			}
+		}
+	}
+
+	list := []string{"Foo", "Bar"}
+
+	complexList := []*A{
+		{"b", "c"},
+		{"d", "e"},
+		{"g", "h"},
+		{"j", "k"},
+	}
+
+	cases := []struct {
+		expected interface{}
+		actual   interface{}
+		result   bool
+	}{
+		{strSeq(list...), "Bar", true},
+		{strSeq(list...), "Salut", false},
+		{complexSeq(complexList...), &A{"g", "h"}, true},
+		{complexSeq(complexList...), &A{"g", "e"}, false},
+	}
+
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("Contains(%#v, %#v)", seqToSlice(c.expected), seqToSlice(c.actual)), func(t *testing.T) {
+			mockT := new(testing.T)
+			res := Contains(mockT, c.expected, c.actual)
+
+			if res != c.result {
+				if res {
+					t.Errorf(
+						"Contains(%#v, %#v) should return true:\n\t%#v contains %#v",
+						seqToSlice(c.expected), seqToSlice(c.actual), seqToSlice(c.expected), seqToSlice(c.actual))
+				} else {
+					t.Errorf(
+						"Contains(%#v, %#v) should return false:\n\t%#v does not contain %#v",
+						seqToSlice(c.expected), seqToSlice(c.actual), seqToSlice(c.expected), seqToSlice(c.actual))
+				}
+			}
+		})
+	}
+
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("NotContains(%#v, %#v)", c.expected, c.actual), func(t *testing.T) {
+			mockT := new(testing.T)
+			res := NotContains(mockT, c.expected, c.actual)
+
+			// NotContains should be inverse of Contains. If it's not, something is wrong
+			if res == Contains(mockT, c.expected, c.actual) {
+				if res {
+					t.Errorf("NotContains(%#v, %#v) should return true:\n\t%#v does not contains %#v", c.expected, c.actual, c.expected, c.actual)
+				} else {
+					t.Errorf("NotContains(%#v, %#v) should return false:\n\t%#v contains %#v", c.expected, c.actual, c.expected, c.actual)
+				}
+			}
+		})
+	}
+}

assert/seq_supported.go

@@ -0,0 +1,44 @@
+//go:build go1.23 || goexperiment.rangefunc
+
+package assert
+
+import "reflect"
+
+var (
+	boolType = reflect.TypeOf(true)
+)
+
+// seqToSlice checks if x is a sequence, and converts it to a slice of the
+// same element type. Otherwise, x is returned as-is.
+func seqToSlice(x interface{}) interface{} {
+	if x == nil {
+		return nil
+	}
+
+	xv := reflect.ValueOf(x)
+	xt := xv.Type()
+	// We're looking for a function with exactly one input parameter and no return values.
+	if xt.Kind() != reflect.Func || xt.NumIn() != 1 || xt.NumOut() != 0 {
+		return x
+	}
+
+	// The input parameter should be of type func(T) bool
+	paramType := xt.In(0)
+	if paramType.Kind() != reflect.Func || paramType.NumIn() != 1 || paramType.NumOut() != 1 || paramType.Out(0) != boolType {
+		return x
+	}
+
+	elemType := paramType.In(0)
+	resultType := reflect.SliceOf(elemType)
+	result := reflect.MakeSlice(resultType, 0, 0)
+
+	yieldFunc := reflect.MakeFunc(paramType, func(args []reflect.Value) []reflect.Value {
+		result = reflect.Append(result, args[0])
+		return []reflect.Value{reflect.ValueOf(true)}
+	})
+
+	// Call the function with the yield function as the argument
+	xv.Call([]reflect.Value{yieldFunc})
+
+	return result.Interface()
+}

assert/seq_unsupported.go

@@ -0,0 +1,9 @@
+//go:build !go1.23 && !goexperiment.rangefunc
+
+package assert
+
+// seqToSlice would convert a sequence of elements to a slice of the respective type.
+// However, since sequences are not supported given the build tags, it just returns x as-is.
+func seqToSlice(x interface{}) interface{} {
+	return x
+}