Update Go version support to 1.18 and onward

.github/workflows/main.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go_version: ["1.18.1", "1.17.6", "1.16.5"]
+        go_version: ["1.20", "1.19", "1.18"]
     steps:
       - uses: actions/checkout@v3
       - name: Setup Go

README.md

@@ -348,7 +348,7 @@ To update Testify to the latest version, use `go get -u github.com/stretchr/test
 Supported go versions
 ==================
 
-We currently support the most recent major Go versions from 1.13 onward.
+We currently support the most recent major Go versions from 1.18 onward.
 
 ------
 

assert/assertions.go

@@ -91,7 +91,7 @@ func copyExportedFields(expected interface{}) interface{} {
 		result := reflect.New(expectedType).Elem()
 		for i := 0; i < expectedType.NumField(); i++ {
 			field := expectedType.Field(i)
-			isExported := field.PkgPath == "" // should use field.IsExported() but it's not available in Go 1.16.5
+			isExported := field.IsExported()
 			if isExported {
 				fieldValue := expectedValue.Field(i)
 				if isNil(fieldValue) || isNil(fieldValue.Interface()) {

go.mod

@@ -1,6 +1,6 @@
 module github.com/stretchr/testify
 
-go 1.13
+go 1.20
 
 require (
 	github.com/davecgh/go-spew v1.1.1