From 4cad9445ec9c4a76417c2237d7e783fe4741ce2b Mon Sep 17 00:00:00 2001
From: John Lambert <john_lambert@sil.org>
Date: Tue, 26 Nov 2024 14:19:06 -0500
Subject: [PATCH] Allow for zero corpora

---
 src/SIL.Machine/Corpora/NParallelTextCorpus.cs            | 2 --
 .../SIL.Machine.Tests/Corpora/NParallelTextCorpusTests.cs | 8 ++++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/SIL.Machine/Corpora/NParallelTextCorpus.cs b/src/SIL.Machine/Corpora/NParallelTextCorpus.cs
index c8f2c904..d3df81da 100644
--- a/src/SIL.Machine/Corpora/NParallelTextCorpus.cs
+++ b/src/SIL.Machine/Corpora/NParallelTextCorpus.cs
@@ -12,8 +12,6 @@ public class NParallelTextCorpus : NParallelTextCorpusBase
         public NParallelTextCorpus(IEnumerable<ITextCorpus> corpora, IComparer<object> rowRefComparer = null)
         {
             Corpora = corpora.ToImmutableArray();
-            if (Corpora.Count < 1)
-                throw new ArgumentException("There must be at least one corpora.", nameof(corpora));
             RowRefComparer = rowRefComparer ?? new DefaultRowRefComparer();
             AllRows = new bool[Corpora.Count]
                 .Select(_ => false)
diff --git a/tests/SIL.Machine.Tests/Corpora/NParallelTextCorpusTests.cs b/tests/SIL.Machine.Tests/Corpora/NParallelTextCorpusTests.cs
index 68dc9f90..e07c23ce 100644
--- a/tests/SIL.Machine.Tests/Corpora/NParallelTextCorpusTests.cs
+++ b/tests/SIL.Machine.Tests/Corpora/NParallelTextCorpusTests.cs
@@ -6,6 +6,14 @@ namespace SIL.Machine.Corpora;
 [TestFixture]
 public class NParallelTextCorpusTests
 {
+    [Test]
+    public void GetRows_ZeroCorpora()
+    {
+        var nParallelCorpus = new NParallelTextCorpus([]);
+        NParallelTextRow[] rows = nParallelCorpus.ToArray();
+        Assert.That(rows.Length, Is.EqualTo(0));
+    }
+
     [Test]
     public void GetRows_ThreeCorpora()
     {