From d4fd866ce3f743961d41a7cda96ab450320b81c6 Mon Sep 17 00:00:00 2001
From: Justin Santa Barbara <justin@fathomdb.com>
Date: Wed, 14 Dec 2016 11:41:17 -0500
Subject: [PATCH] Fix a bug in diff formatting

---
 pkg/diff/diff.go      |  5 ++++-
 pkg/diff/diff_test.go | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/pkg/diff/diff.go b/pkg/diff/diff.go
index 4c6c25505a..4ad9cb8ef1 100644
--- a/pkg/diff/diff.go
+++ b/pkg/diff/diff.go
@@ -121,7 +121,10 @@ func buildDiffLines(lString, rString string) []lineRecord {
 			}
 
 		case diffmatchpatch.DiffEqual:
-			if len(lines) > 0 {
+			if len(lines) == 1 {
+				l += lines[0]
+				r += lines[0]
+			} else if len(lines) > 1 {
 				if l != "" || r != "" {
 					l += lines[0]
 					r += lines[0]
diff --git a/pkg/diff/diff_test.go b/pkg/diff/diff_test.go
index cf1b016a81..7f8bdb7b74 100644
--- a/pkg/diff/diff_test.go
+++ b/pkg/diff/diff_test.go
@@ -117,3 +117,22 @@ F2`
 		t.Fatalf("unexpected diff.  expected=%v, actual=%v", expectedDiff, actual)
 	}
 }
+
+
+func Test_Diff_ChangedLine(t *testing.T) {
+	l := `ABC123
+Line2
+Line3`
+	r := `ABCDEF
+Line2
+Line3`
+	expectedDiff := `+ ABCDEF
+- ABC123
+  Line2
+  Line3
+`
+	actual := FormatDiff(l, r)
+	if actual != expectedDiff {
+		t.Fatalf("unexpected diff.  expected=%v, actual=%v", expectedDiff, actual)
+	}
+}