Bug Fix: The value in the setvar should be able to start with - or +. (…

…#1125)

* Fix setvar to take the value as ---test

* Resolve comment

internal/actions/setvar.go

@@ -145,16 +145,23 @@ func (a *setvarFn) evaluateTxCollection(r plugintypes.RuleMetadata, tx plugintyp
 	case len(value) == 0:
 		// if nothing to input
 		col.Set(key, []string{""})
-	case value[0] == '+', value[0] == '-': // Increment or decrement, arithmetical operations
+	// Check if this could be an arithemetic operation. If it is followed by a number, it will be treated as an arithmetic operation. Otherwise, it will be treated as a string.
+	case value[0] == '+', value[0] == '-':
 		val := 0
 		if len(value) > 1 {
 			val, err = strconv.Atoi(value[1:])
 			if err != nil {
-				tx.DebugLogger().Error().
-					Str("var_value", value).
-					Int("rule_id", r.ID()).
-					Err(err).
-					Msg("Invalid value")
+				// If the variable doesn't exist, we would need to raise an error. Otherwise, it should be the same value.
+				if strings.HasPrefix(value[1:], "tx.") {
+					tx.DebugLogger().Error().
+						Str("var_value", value).
+						Int("rule_id", r.ID()).
+						Err(err).
+						Msg(value)
+					return
+				}
+
+				col.Set(key, []string{value})
 				return
 			}
 		}

internal/actions/setvar_test.go

@@ -96,6 +96,18 @@ func TestSetvarEvaluate(t *testing.T) {
 			init:                     "TX.newvar=-%{tx.missingvar}",
 			expectInvalidSyntaxError: true,
 		},
+		{
+			name:                     "Non Numerical Operation - If the value starts with -",
+			init:                     "TX.newvar=----expected_value",
+			expectInvalidSyntaxError: false,
+			expectNewVarValue:        "----expected_value",
+		},
+		{
+			name:                     "Non Numerical Operation - If the value starts with +",
+			init:                     "TX.newvar=+++expected_value",
+			expectInvalidSyntaxError: false,
+			expectNewVarValue:        "+++expected_value",
+		},
 	}
 
 	for _, tt := range tests {