truncate SPs with precision and add tests for this

Author: rerpha

app/components/InstrumentPage.test.ts

@@ -1,10 +1,11 @@
-import { ConfigOutput, IfcPVWSRequest } from "@/app/types";
+import { ConfigOutput, IfcBlock, IfcPVWSRequest } from "@/app/types";
 import {
   getGroupsWithBlocksFromConfigOutput,
   RC_ENABLE,
   RC_INRANGE,
   SP,
   subscribeToBlockPVs,
+  toPrecision,
 } from "@/app/components/InstrumentPage";
 
 test("subscribeToBlockPVs subscribes to all run control PVs", () => {
@@ -21,6 +22,37 @@ test("subscribeToBlockPVs subscribes to all run control PVs", () => {
   );
 });
 
+test("toPrecision does nothing to string value ", () => {
+  const expectedValue = "untouched";
+  const aBlock: IfcBlock = {
+    pvaddress: "SOME:BLOCK:STR",
+    value: expectedValue,
+  };
+  expect(toPrecision(aBlock, expectedValue)).toBe(expectedValue);
+});
+
+test("toPrecision does nothing to block without pv ", () => {
+  const expectedValue = 0.00123456;
+  const aBlock: IfcBlock = {
+    pvaddress: "SOME:BLOCK:STR",
+    value: expectedValue,
+  };
+  expect(toPrecision(aBlock, expectedValue)).toBe(expectedValue);
+});
+
+test("toPrecision truncates block if it has precision", () => {
+  const originalValue = 0.00123456;
+  const precision = 3;
+  const aBlock: IfcBlock = {
+    pvaddress: "SOME:BLOCK:STR",
+    value: originalValue,
+    precision: precision,
+  };
+  expect(toPrecision(aBlock, originalValue)).toBe(
+    originalValue.toPrecision(precision),
+  );
+});
+
 test("getGroupsWithBlocksFromConfigOutput gets blocks from blockserver groups", () => {
   const blockNameToTest = "aBlock";
   const groupNameToTest = "aGroup";

app/components/InstrumentPage.tsx

@@ -86,6 +86,15 @@ export function getGroupsWithBlocksFromConfigOutput(
   return newGroups;
 }
 
+export function toPrecision(
+  block: IfcBlock,
+  pvVal: number | string,
+): string | number {
+  return block.precision && typeof pvVal == "number"
+    ? pvVal.toPrecision(block.precision)
+    : pvVal;
+}
+
 function InstrumentData({ instrumentName }: { instrumentName: string }) {
   // set up the different states for the instrument data
 
@@ -232,12 +241,9 @@ function InstrumentData({ instrumentName }: { instrumentName: string }) {
                 // this is likely the first update, and contains precision information which is not repeated on a normal value update - store this in the block for later truncation (see below)
                 block.precision = prec;
               }
-              if (block.precision && typeof pvVal == "number") {
-                // if a block has precision truncate it here
-                block.value = pvVal.toPrecision(block.precision);
-              } else {
-                block.value = pvVal;
-              }
+              // if a block has precision truncate it here
+              block.value = toPrecision(block, pvVal);
+
               if (updatedPV.units) block.units = updatedPV.units;
               if (updatedPV.severity) block.severity = updatedPV.severity;
             } else if (updatedPVName == block_full_pv_name + RC_INRANGE) {
@@ -247,7 +253,7 @@ function InstrumentData({ instrumentName }: { instrumentName: string }) {
               block.runcontrol_enabled = updatedPV.value == 1;
               return;
             } else if (updatedPVName == block_full_pv_name + SP) {
-              block.sp_value = pvVal;
+              block.sp_value = toPrecision(block, pvVal);
               return;
             }
           }