CSV dummy file used in all scenarios

BAS files containing VBA code for creation and import of CSV file
XLS file containing worksheet with formulas used to generate random data for CSV file
Updated README

README.md

 # Covid-19 Excel error analysis
+This repository contains the following files
+* covid_test_data.csv<br>
+  This is the dummy CSV file we created to test several scenarios that might have led to the COVID-19 Excel error by NHS Track-and-trace
+* modCSVCreator.bas<br>
+  This file contains the createCovidTestsCSV() VBA subroutine that was used to create the dummy CSV file above. In order to run it you need the xls file below that contains a worksheet containing random data generated by Excel formulas. 
+* RandomCSVCreator.xls<br>
+  This Excel workbook contains a worksheet with random data used by modCSVCreator.bas to add in the dummy CSV file.
+* modImportLargeCSV.bas<br>
+  This Excel VBA module contains the subroutine used to test importing a large CSV using VBA.
 

modCSVCreator.bas

+Attribute VB_Name = "modCSVCreator"
+Option Explicit
+'Create a new COVID-19 dummy CSV file by running this subroutine
+'Download file RandomCSVCreator.xls which contains worksheet shRandomData
+Sub createCovidTestsCSV()
+Dim filename As String
+Dim rowsStored As Long, rowsReturned As Long
+filename = getFilename
+Open filename For Output As #1
+Debug.Print "CSV creation started at " & Time
+rowsStored = 0
+Do
+    Print #1, getCSVPayload(rowsStored, rowsReturned)
+    rowsStored = rowsStored + rowsReturned
+    Debug.Print rowsStored
+Loop Until rowsStored > 2 ^ 20
+Close #1
+Debug.Print "CSV creation ended at " & Time
+End Sub
+
+Function getFilename()
+getFilename = Application.GetSaveAsFilename
+End Function
+
+Function getCSVPayload(rowsStored As Long, ByRef rowsReturned As Long) As String
+Dim randomData As Variant
+Dim currentRng As Range
+Dim i As Long, j As Integer
+Dim csvRows() As String, csvRow(1 To 8) As String
+Set currentRng = shRandomData.Range("A1").CurrentRegion
+If rowsStored > 0 Then
+    Set currentRng = shRandomData.Range("A1").CurrentRegion.Offset(1, 0).Resize(currentRng.Rows.Count - 1)
+    shRandomData.Calculate
+End If
+randomData = currentRng.Value
+ReDim csvRows(1 To currentRng.Rows.Count)
+For i = LBound(csvRows, 1) To UBound(csvRows, 1)
+    For j = 1 To 8
+        csvRow(j) = randomData(i, j)
+    Next j
+    csvRows(i) = Join(csvRow, ",")
+    DoEvents
+Next i
+getCSVPayload = Join(csvRows, vbNewLine)
+rowsReturned = currentRng.Rows.Count
+End Function

modImportLargeCSV.bas

+Attribute VB_Name = "modImportLargeCSV"
+Option Explicit
+
+Sub ImportLargeCSVTest()
+    Dim ImpRng As Range
+    Dim Filename As String
+    Dim r As Long
+    Dim Data, parts
+    Dim i As Integer
+    
+    Set ImpRng = ActiveCell
+    On Error Resume Next
+    Filename = "C:\Users\ddimak\Documents\courses\VBA Part 3\National_Statistics_Postcode_Lookup_UK.csv"
+    Open Filename For Input As #1
+    If Err <> 0 Then
+        MsgBox "Not found: " & Filename, vbCritical, "ERROR"
+        Exit Sub
+    End If
+    On Error GoTo 0
+    
+    r = 0
+    Do Until EOF(1)
+        Line Input #1, Data
+        parts = Split(Data, ",")
+        Range(ImpRng.Offset(r, 0), ImpRng.Offset(r, UBound(parts))).Value = parts
+        r = r + 1
+        DoEvents
+    Loop
+    Close #1
+End Sub