From 85c1fb77eca14f2b0c0c530cad67805ecd6db644 Mon Sep 17 00:00:00 2001
From: Mats Alm <897655+swmal@users.noreply.github.com>
Date: Tue, 6 Jul 2021 11:16:39 +0200
Subject: [PATCH] #427 - Validation of datavalidations throw an exception when
 Formula1 is empty even if AllowBlank was set to true

---
 src/EPPlus/DataValidation/ExcelDataValidation.cs  |  2 +-
 .../DataValidation/DataValidationTests.cs         | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/EPPlus/DataValidation/ExcelDataValidation.cs b/src/EPPlus/DataValidation/ExcelDataValidation.cs
index 5593a9d23..b2beab8ab 100644
--- a/src/EPPlus/DataValidation/ExcelDataValidation.cs
+++ b/src/EPPlus/DataValidation/ExcelDataValidation.cs
@@ -253,7 +253,7 @@ public virtual void Validate()
         {
             var address = Address.Address;
             // validate Formula1
-            if (string.IsNullOrEmpty(Formula1Internal))
+            if (string.IsNullOrEmpty(Formula1Internal) && !(AllowBlank ?? false))
             {
                 throw new InvalidOperationException("Validation of " + address + " failed: Formula1 cannot be empty");
             }
diff --git a/src/EPPlusTest/DataValidation/DataValidationTests.cs b/src/EPPlusTest/DataValidation/DataValidationTests.cs
index 72fa92944..7d100cf3e 100644
--- a/src/EPPlusTest/DataValidation/DataValidationTests.cs
+++ b/src/EPPlusTest/DataValidation/DataValidationTests.cs
@@ -154,6 +154,21 @@ public void DataValidations_ShouldAcceptOneItemOnly()
             validation.Validate();
         }
 
+        [TestMethod]
+        public void DataValidations_ShouldNotThrowIfAllowBlankIsSet()
+        {
+            var validation = _sheet.DataValidations.AddListValidation("A1");
+            validation.AllowBlank = true;
+            validation.Validate();
+        }
+
+        [TestMethod, ExpectedException(typeof(InvalidOperationException))]
+        public void DataValidations_ShouldThrowIfAllowBlankIsNotSet()
+        {
+            var validation = _sheet.DataValidations.AddListValidation("A1");
+            validation.Validate();
+        }
+
         [TestMethod]
         public void ExcelDataValidation_ShouldReplaceLastPartInWholeColumnRangeWithMaxNumberOfRowsOneColumn()
         {