Added basic assert functions

Contains.go

@@ -0,0 +1,95 @@
+package assert
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// Contains asserts that a contains b.
+func Contains(t testing.TB, a any, b any) {
+	if contains(a, b) {
+		return
+	}
+
+	t.Errorf(`
+file:     %s
+assert:   Contains
+container:%v
+element:  %v`, file(t), a, b)
+	t.FailNow()
+}
+
+// NotContains asserts that a doesn't contain b.
+func NotContains(t testing.TB, a any, b any) {
+	if !contains(a, b) {
+		return
+	}
+
+	t.Errorf(`
+file:     %s
+assert:   NotContains
+container:%v
+element:  %v`, file(t), a, b)
+	t.FailNow()
+}
+
+// contains returns whether container contains the given the element.
+// It works with strings, maps and slices.
+func contains(container any, element any) bool {
+	containerValue := reflect.ValueOf(container)
+
+	switch containerValue.Kind() {
+	case reflect.String:
+		elementValue := reflect.ValueOf(element)
+		return strings.Contains(containerValue.String(), elementValue.String())
+
+	case reflect.Map:
+		keys := containerValue.MapKeys()
+
+		for _, key := range keys {
+			if key.Interface() == element {
+				return true
+			}
+		}
+
+	case reflect.Slice:
+		elementValue := reflect.ValueOf(element)
+
+		if elementValue.Kind() == reflect.Slice {
+			elementLength := elementValue.Len()
+
+			if elementLength == 0 {
+				return true
+			}
+
+			if elementLength > containerValue.Len() {
+				return false
+			}
+
+			matchingElements := 0
+
+			for i := 0; i < containerValue.Len(); i++ {
+				if containerValue.Index(i).Interface() == elementValue.Index(matchingElements).Interface() {
+					matchingElements++
+				} else {
+					matchingElements = 0
+				}
+
+				if matchingElements == elementLength {
+					return true
+				}
+			}
+
+			return false
+		}
+
+		for i := 0; i < containerValue.Len(); i++ {
+			if containerValue.Index(i).Interface() == element {
+				return true
+			}
+		}
+	}
+
+	return false
+}