fix(pkg/strvals): evaluate "null" values

resolves #3891
Co-authored-by: Matthew Fisher <matt.fisher@microsoft.com>

pkg/strvals/parser.go

@@ -82,6 +82,10 @@ func ParseIntoString(s string, dest map[string]interface{}) error {
 
 // parser is a simple parser that takes a strvals line and parses it into a
 // map representation.
+//
+// where sc is the source of the original data being parsed
+// where data is the final parsed data from the parses with correct types
+// where st is a boolean to figure out if we're forcing it to parse values as string
 type parser struct {
 	sc   *bytes.Buffer
 	data map[string]interface{}
@@ -329,6 +333,10 @@ func typedVal(v []rune, st bool) interface{} {
 		return false
 	}
 
+	if strings.EqualFold(val, "null") {
+		return nil
+	}
+
 	// If this value does not start with zero, and not returnString, try parsing it to an int
 	if !st && len(val) != 0 && val[0] != '0' {
 		if iv, err := strconv.ParseInt(val, 10, 64); err == nil {

pkg/strvals/parser_test.go

@@ -81,6 +81,11 @@ func TestParseSet(t *testing.T) {
 		expect map[string]interface{}
 		err    bool
 	}{
+		{
+			"name1=null,f=false,t=true",
+			map[string]interface{}{"name1": nil, "f": false, "t": true},
+			false,
+		},
 		{
 			"name1=value1",
 			map[string]interface{}{"name1": "value1"},