fix(mocks): keep a leading blank, and round a date the way the text branch does

Three findings from review.

- viewdata trimmed both ends of a character cell. A leading blank is part of a
  SAS character value and the viewer renders it; only the trailing blanks SAS
  pads to are noise, so the cell is trimmed at the end and an all-blank cell is
  still SAS missing. viewdata-cells.test.js fails on the previous version.
- viewDate floored a stored day count while the ISO branch rounded, so the same
  instant could land on different days depending on how the row carried it. Both
  round now.
- the two label members stay different. The finding was that cols[].LABEL uses
  the data dictionary business label while $viewdata.vars[.].label uses the
  physical one; the recorded estate response does exactly that - cols DSN is
  "Dataset Name to be edited", $viewdata.vars.DSN.label is "DSN" - so unifying
  them would break parity. The comment says so, and a test asserts the split
  against the recorded answer so the next reader does not tidy it away.

sas/mocks/sasjs/services/public/viewdata.js

@@ -51,7 +51,9 @@ function viewDateTime(seconds) {
 }
 
 function viewDate(seconds) {
-    const d = new Date(SAS_EPOCH_MS + Math.floor(seconds) * 86400000)
+    // whole days, rounded as the text branch rounds, so a stored number and a
+    // stored ISO string of the same instant land on the same day
+    const d = new Date(SAS_EPOCH_MS + Math.round(seconds) * 86400000)
     // DATE9. is four digits wide, so a year below 1000 is zero-padded
     return pad2(d.getUTCDate()) + VIEW_MONTHS[d.getUTCMonth()] + pad4(d.getUTCFullYear())
 }
@@ -282,9 +284,15 @@ if (tableData && tableData.columns) {
             if (val === undefined || val === null || val === '') {
                 row[col.name] = col.type === 'N' ? '.' : ' '
             } else {
+                /*
+                  Only the trailing blanks are noise - the width SAS pads to.
+                  A leading blank is part of the value and the viewer shows it,
+                  so the text is trimmed at the end only.
+                */
+                const text = String(val).replace(/\s+$/, '')
                 row[col.name] = typeof val === 'number'
-                ? String(val)
-                : (String(val).trim() === '' ? ' ' : String(val).trim())
+                    ? String(val)
+                    : (text === '' ? ' ' : text)
             }
         }
         return row
@@ -310,6 +318,13 @@ if (tableData && tableData.columns) {
       bytes, DATETIME19.3. sasVarsEntry describes the *edit grid*, where the
       temporal columns have been converted to character, so it is not used here.
     */
+    /*
+      The two label members are deliberately different, and the recorded
+      response proves it: cols[].LABEL for DSN is "Dataset Name to be edited"
+      (the data dictionary's business label, which viewdata.sas augments in as
+      it does for getdata) while $viewdata.vars.DSN.label is "DSN", the physical
+      label. Unifying them would look tidier and would stop matching the estate.
+    */
     vars = {}
     for (const col of physicalColumns) {
         const isTemporal = ['DATE', 'DATETIME', 'TIME'].indexOf(getDdType(col)) >= 0

sas/mocks/test/viewdata-cells.test.js

@@ -0,0 +1,55 @@
+/**
+ * Character cells and labels in the viewer's payload.
+ *
+ * Two rules the recorded response fixes, both of which look like bugs from the
+ * inside and are parity from the outside.
+ */
+const test = require('node:test')
+const assert = require('node:assert')
+const fs = require('node:fs')
+const path = require('node:path')
+
+const { seededEstate, runService } = require('./harness')
+
+function viewOf(estate, libds) {
+  const body = JSON.parse(
+    runService(estate, 'public/viewdata', {
+      tableName: 'SASControlTable',
+      rows: [{ LIBDS: libds, FILTER_RK: -1 }]
+    })
+  )
+  assert.equal(body.sasjsAbort, undefined)
+  return body
+}
+
+test('a character cell keeps a leading blank and loses only the padding', () => {
+  const estate = seededEstate({ demo: false })
+  const table = {
+    columns: [{ name: 'C', type: 'char', length: 10 }],
+    rows: [{ C: ' ABC' }, { C: 'ABC   ' }, { C: '   ' }]
+  }
+  fs.writeFileSync(
+    path.join(estate.appDir, 'data', 'DC_JSLIB', 'mpe_x_cells.json'),
+    JSON.stringify(table)
+  )
+
+  const rows = viewOf(estate, 'DC_JSLIB.MPE_X_CELLS').viewdata
+
+  // a leading blank is part of the value, and the viewer shows it
+  assert.equal(rows[0].C, ' ABC')
+  // trailing blanks are the width SAS pads to
+  assert.equal(rows[1].C, 'ABC')
+  // an all-blank cell is SAS missing
+  assert.equal(rows[2].C, ' ')
+})
+
+test('cols and $viewdata report the labels the estate reports', () => {
+  // the recorded response has cols[].LABEL for DSN as the data dictionary's
+  // business label and $viewdata.vars.DSN.label as the physical label - two
+  // members, two answers, and the estate is the authority
+  const body = viewOf(seededEstate({ demo: false }), 'DC_JSLIB.MPE_TABLES')
+
+  const dsn = body.cols.find((c) => c.NAME === 'DSN')
+  assert.equal(dsn.LABEL, 'Dataset Name to be edited')
+  assert.equal(body.$viewdata.vars.DSN.label, 'DSN')
+})