From 79892344b86454e8e7f576d7f2790d3923a4ff5f Mon Sep 17 00:00:00 2001
From: acpaquette <acpaquette@usgs.gov>
Date: Tue, 9 Jan 2024 22:04:03 -0700
Subject: [PATCH 1/4] Fixed env var expansion to include underscores

---
 isis/src/base/objs/FileName/FileName.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/isis/src/base/objs/FileName/FileName.cpp b/isis/src/base/objs/FileName/FileName.cpp
index 8927da9636..425e0801a5 100644
--- a/isis/src/base/objs/FileName/FileName.cpp
+++ b/isis/src/base/objs/FileName/FileName.cpp
@@ -846,7 +846,7 @@ namespace Isis {
     // Loop while there are any "$" at the current position or after
     // Some "$" might be skipped if no translation can be found
     while((varStartPos = expandedStr.indexOf("$", varSearchStartPos)) != -1) {
-      int varEndPos = expandedStr.indexOf(QRegExp("[^a-zA-Z{}0-9]"), varStartPos + 1);
+      int varEndPos = expandedStr.indexOf(QRegExp("[^a-zA-Z{}0-9_]"), varStartPos + 1);
       if (varEndPos == -1)
         varEndPos = expandedStr.length();
 

From 67fe160de2ba67737d229a6b204f938bd0601535 Mon Sep 17 00:00:00 2001
From: acpaquette <acpaquette@usgs.gov>
Date: Tue, 9 Jan 2024 22:21:01 -0700
Subject: [PATCH 2/4] Added test to cover change

---
 isis/tests/FileNameTests.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/isis/tests/FileNameTests.cpp b/isis/tests/FileNameTests.cpp
index fc8aa4b345..ad63edaf2e 100644
--- a/isis/tests/FileNameTests.cpp
+++ b/isis/tests/FileNameTests.cpp
@@ -84,13 +84,21 @@ TEST(FileName, Extension) {
   EXPECT_EQ("cub", file.extension());
 }
 
-TEST(FileName, Expanded) {
+TEST(FileName, Expanded1) {
   QString relativeFileName("test.cub");
   FileName file("$ISISROOT/" + relativeFileName);
   QString isisRoot(getenv("ISISROOT"));
   EXPECT_EQ(isisRoot + "/" + relativeFileName, file.expanded());
 }
 
+TEST(FileName, Expanded2) {
+  QString relativeFileName("test.cub");
+  setenv("SOME_FILE_PATH", getenv("ISISROOT"), 1);
+  FileName file("$SOME_FILE_PATH/" + relativeFileName);
+  QString someFilePath(getenv("ISISROOT"));
+  EXPECT_EQ(someFilePath + "/" + relativeFileName, file.expanded());
+}
+
 TEST(FileName, Original) {
   QString test = "$ISISROOT/testy/mc/test/face/test.cub";
   FileName file(test);

From cf520f619ecefc9e986672a3bfb99c34bae6c188 Mon Sep 17 00:00:00 2001
From: acpaquette <acpaquette@usgs.gov>
Date: Tue, 9 Jan 2024 22:22:59 -0700
Subject: [PATCH 3/4] Added changelog entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54b208fc7a..586552d836 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,7 @@ release.
 
 ### Fixed
 - Fixed <i>noproj</i> bug where missing shapemodel-related keywords (RayTraceEngine, BulletParts, Tolerance) are dropped when the output label is created. This resulted in the Bullet collision detection engine not being used. Issue: [#5377](https://github.com/USGS-Astrogeology/ISIS3/issues/5377)
+- Fixed ISIS failing to expand env variables with an "_" in them. [#5402](https://github.com/DOI-USGS/ISIS3/pull/5402)
 
 ## [8.1.0] - 2023-12-05
 

From 194162aa5c24a5bebb93aeb3a3c8c0be1f71a77d Mon Sep 17 00:00:00 2001
From: acpaquette <acpaquette@usgs.gov>
Date: Fri, 12 Jan 2024 13:59:12 -0700
Subject: [PATCH 4/4] Renamed tests

---
 isis/tests/FileNameTests.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/isis/tests/FileNameTests.cpp b/isis/tests/FileNameTests.cpp
index ad63edaf2e..ce19019a71 100644
--- a/isis/tests/FileNameTests.cpp
+++ b/isis/tests/FileNameTests.cpp
@@ -84,14 +84,14 @@ TEST(FileName, Extension) {
   EXPECT_EQ("cub", file.extension());
 }
 
-TEST(FileName, Expanded1) {
+TEST(FileName, ExpandedDefault) {
   QString relativeFileName("test.cub");
   FileName file("$ISISROOT/" + relativeFileName);
   QString isisRoot(getenv("ISISROOT"));
   EXPECT_EQ(isisRoot + "/" + relativeFileName, file.expanded());
 }
 
-TEST(FileName, Expanded2) {
+TEST(FileName, ExpandedUnderscore) {
   QString relativeFileName("test.cub");
   setenv("SOME_FILE_PATH", getenv("ISISROOT"), 1);
   FileName file("$SOME_FILE_PATH/" + relativeFileName);