Disallow negative tolerance value in save&restore

Author: georgweiss

app/save-and-restore/app/src/main/java/org/phoebus/applications/saveandrestore/ui/configuration/ConfigurationController.java

@@ -309,7 +309,13 @@ public String toString(Double value) {
             @Override
             public Double fromString(String string) {
                 try {
-                    return Double.parseDouble(string);
+                    Double value = Double.parseDouble(string);
+                    if(value < 0){
+                        // Tolerance must be >= 0.
+                        // Tolerance must be >= 0.
+                        return null;
+                    }
+                    return value;
                 } catch (Exception e) {
                     // No logging needed: user has entered text that cannot be parsed as double.
                     return null;

services/save-and-restore/src/main/java/org/phoebus/service/saveandrestore/web/controllers/ConfigurationController.java

@@ -71,8 +71,8 @@ else if(configPv.getTolerance() != null){
                 if(configPv.getPvCompareMode() == null){
                     throw new IllegalArgumentException("PV item \"" + configPv.getPvName() + "\" specifies tolerance but no comparison mode");
                 }
-                //...but is zero, which does not make sense.
-                else if(configPv.getTolerance() == 0){
+                //...but is less than zero, which does not make sense as comparison considers tolerance as upper and lower limit.
+                else if(configPv.getTolerance() < 0 ){
                     throw new IllegalArgumentException("PV item \"" + configPv.getPvName() + "\" specifies zero tolerance");
                 }
              }

services/save-and-restore/src/test/java/org/phoebus/service/saveandrestore/web/controllers/ConfigurationControllerTest.java

@@ -196,7 +196,7 @@ public void testCreateInvalidConfiguration() throws Exception {
 
         configurationData.setPvList(List.of(
                 ConfigPv.builder().pvName("fooo").readbackPvName("bar").pvCompareMode(PvCompareMode.RELATIVE)
-                        .tolerance(0.0).build()));
+                        .tolerance(-0.1).build()));
 
         configuration.setConfigurationData(configurationData);