Modified gotest template files allowing for enhanced error testing in Go

function.tmpl

{{define "function"}}
{{- $f := .}}

func {{.TestName}}(t *testing.T) {
	{{- with .Receiver}}
		{{- if .IsStruct}}
			{{- if .Fields}}
				type fields struct {
				{{- range .Fields}}
					{{Field .}} {{.Type}}
				{{- end}}
				}
			{{- end}}
		{{- end}}
	{{- end}}
	{{- if .TestParameters}}
	type args struct {
		{{- range .TestParameters}}
				{{Param .}} {{.Type}}
		{{- end}}
	}
	{{- end}}
	tests := []struct {
		name string
		{{- with .Receiver}}
			{{- if and .IsStruct .Fields}}
				fields fields
			{{- else}}
				{{Receiver .}} {{.Type}}
			{{- end}}
		{{- end}}
		{{- if .TestParameters}}
			args args
		{{- end}}
		{{- range .TestResults}}
			{{Want .}} {{.Type}}
		{{- end}}
		{{- if .ReturnsError}}
			wantErr error
		{{- end}}
	}{
		// TODO: Add test cases.
	}
	for {{if (or .Subtests (not .IsNaked))}} _, tt := {{end}} range tests {
        {{- if .Subtests }}t.Run(tt.name, func(t *testing.T) { {{- end -}}
			{{- with .Receiver}}
				{{- if .IsStruct}}
					{{Receiver .}} := {{if .Type.IsStar}}&{{end}}{{.Type.Value}}{
					{{- range .Fields}}
						{{.Name}}: tt.fields.{{Field .}},
					{{- end}}
					}
				{{- end}}
			{{- end}}
			{{- range .Parameters}}
				{{- if .IsWriter}}
					{{Param .}} := &bytes.Buffer{}
				{{- end}}
			{{- end}}
			{{template "results" $f}} {{template "call" $f}}
			{{- if .ReturnsError}}
				if err != nil && tt.wantErr == nil {
					assert.Fail(t, fmt.Sprintf(
						"Error not expected but got one:\n"+
							"error: %q", err),
					)
					{{- if .TestResults}}
						{{if .Subtests }}return{{else}}continue{{end}}
					{{- end}}
				}
				if tt.wantErr != nil {
					assert.EqualError(t, err, tt.wantErr.Error())
					{{- if .TestResults}}
						{{if .Subtests }}return{{else}}continue{{end}}
					{{- end}}
				}
			{{- end}}
			{{- range .TestResults}}
				assert.Equal(t, tt.{{Want .}}, {{Got .}})
			{{- end}}
		{{- if .Subtests }} }) {{- end -}}
	}
}

{{end}}

results.tmpl

{{define "results"}} {{range $i, $el := .Results}}{{if $i}}, {{end}}{{Got .}}{{end}}{{if .ReturnsError}}{{if not .OnlyReturnsError}}, {{end}}err{{end}} {{if or .Results .ReturnsError}} := {{end}} {{end}}