rules/sdk: exclude "testutil" from map ranging checks

This change excludes "testutil" from map ranging checks
given that such code is used for testing and no need to flag
natural code to iterate over tests.

Fixes #50

rules/sdk/iterate_over_maps.go

@@ -37,7 +37,24 @@ func (mr *mapRanging) ID() string {
 	return mr.MetaData.ID
 }
 
+// There are some packages that inherently need map ranging such as "testutil"
+// so return true if we detect such.
+func pkgExcusedFromMapRangingChecks(ctx *gosec.Context) bool {
+	switch pkg := ctx.Pkg.Name(); pkg {
+	case "testutil":
+		return true
+	default:
+		return false
+	}
+}
+
 func (mr *mapRanging) Match(node ast.Node, ctx *gosec.Context) (*gosec.Issue, error) {
+	if pkgExcusedFromMapRangingChecks(ctx) {
+		// Do nothing for such packages like "testutil".
+		// Please see https://github.com/cosmos/gosec/issues/50
+		return nil, nil
+	}
+
 	rangeStmt, ok := node.(*ast.RangeStmt)
 	if !ok {
 		return nil, nil