From 8b0031ca713d1a2b53db891217a45e802d775fea Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Wed, 7 Jan 2026 06:33:10 +0000
Subject: [PATCH] add tests for 'yh' motion

---
 fcore/normal-mode/normal-yank.sml |  2 +-
 shf-tests.mlb                     |  1 +
 temp.txt                          |  2 +-
 test/normal-yank.sml              | 95 +++++++++++++++++++++++++++++++
 test/test-utils.sml               | 30 ++++++++++
 test/test.sml                     | 14 ++---
 todo.md                           |  3 +-
 7 files changed, 136 insertions(+), 11 deletions(-)
 create mode 100644 test/normal-yank.sml

diff --git a/fcore/normal-mode/normal-yank.sml b/fcore/normal-mode/normal-yank.sml
index 60851f7..1521e13 100644
--- a/fcore/normal-mode/normal-yank.sml
+++ b/fcore/normal-mode/normal-yank.sml
@@ -10,7 +10,7 @@ struct
 
       val buffer = LineGap.goToIdx (cursorIdx, buffer)
       val min = Cursor.vi0 (buffer, cursorIdx)
-      val low = Cursor.viH (buffer, cursorIdx, 1)
+      val low = Cursor.viH (buffer, cursorIdx, count)
 
       val low = Int.max (min, low)
       val length = cursorIdx - low
diff --git a/shf-tests.mlb b/shf-tests.mlb
index e6f423b..82ef7eb 100644
--- a/shf-tests.mlb
+++ b/shf-tests.mlb
@@ -70,5 +70,6 @@ test/regex-tests.sml
 test/test-utils.sml
 test/normal-move.sml
 test/normal-delete.sml
+test/normal-yank.sml
 test/regression.sml
 test/test.sml
diff --git a/temp.txt b/temp.txt
index 36fba7d..3b18e51 100644
--- a/temp.txt
+++ b/temp.txt
@@ -1 +1 @@
-( ( hello ) )
+hello world
diff --git a/test/normal-yank.sml b/test/normal-yank.sml
new file mode 100644
index 0000000..829c4eb
--- /dev/null
+++ b/test/normal-yank.sml
@@ -0,0 +1,95 @@
+structure NormalYank =
+struct
+  open Railroad
+  open Railroad.Test
+  open InputMsg
+
+  val yhYank = describe "yank motion 'yh'"
+    [ test "yanks empty string when cursor is at index 0" (fn _ =>
+        let
+          (* arrange *)
+          val originalString = "hello world\n"
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, 0)
+
+          (* act *)
+          val app = TestUtils.updateMany (app, "yh")
+
+          (* assert *)
+          val expectedString = ""
+        in
+          TestUtils.expectYank (app, expectedString)
+        end)
+    , test "yanks empty string when character before cursor is a newline"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalString = "hello\nworld\n"
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, 6)
+
+             (* act *)
+             val app = TestUtils.updateMany (app, "yh")
+
+             (* assert *)
+             val expectedString = ""
+           in
+             TestUtils.expectYank (app, expectedString)
+           end)
+    , test "yanks one char to the left when on a non-newline" (fn _ =>
+        let
+          (* arrange *)
+          val originalString = "hello world\n"
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, 5)
+
+          (* act *)
+          val app = TestUtils.updateMany (app, "yh")
+
+          (* assert *)
+          val expectedString = "o"
+        in
+          TestUtils.expectYank (app, expectedString)
+        end)
+    , test "yanks 3 chars when count is 3" (fn _ =>
+        let
+          (* arrange *)
+          val originalIdx = 5
+          val originalString = "hello world\n"
+
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, originalIdx)
+
+          (* act *)
+          val app = TestUtils.updateMany (app, "3yh")
+
+          (* assert *)
+          val expectedString = "llo"
+        in
+          TestUtils.expectYank (app, expectedString)
+        end)
+    , test
+        "yanks from cursor position to start column when \
+        \count is greater than current column"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalIdx = 5
+             val originalString = "hello world\n"
+
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, originalIdx)
+
+             (* act *)
+             val app = TestUtils.updateMany (app, "9yh")
+
+             (* assert *)
+             val expectedString = "hello"
+           in
+             TestUtils.expectYank (app, expectedString)
+           end)
+    ]
+
+
+  val tests = [yhYank]
+end
diff --git a/test/test-utils.sml b/test/test-utils.sml
index 7e84838..881601c 100644
--- a/test/test-utils.sml
+++ b/test/test-utils.sml
@@ -24,4 +24,34 @@ struct
     in
       loop (0, app)
     end
+
+  fun expectYank (app: AppType.app_type, expectedString) =
+    let
+      open MailboxType
+      open DrawMsg
+      open Railroad
+      open Railroad.Test
+
+      fun loop (hd :: tl) =
+            (case hd of
+               DRAW (YANK actualString) =>
+                 if actualString = expectedString then
+                   Expect.isTrue (actualString = expectedString)
+                 else
+                   let
+                     val () = print
+                       ("expectedString = [" ^ expectedString ^ "]\n")
+                     val () = print ("actualString = [" ^ actualString ^ "]\n")
+                     val () = print "\n"
+                   in
+                     Expect.isTrue (actualString = expectedString)
+                   end
+             | _ => loop tl)
+        | loop ([]) =
+            let val () = print "no string yanked\n"
+            in Expect.isTrue false
+            end
+    in
+      loop (#msgs app)
+    end
 end
diff --git a/test/test.sml b/test/test.sml
index 416569a..e4992ba 100644
--- a/test/test.sml
+++ b/test/test.sml
@@ -5,13 +5,13 @@ struct
 
   fun main () =
     let
-      val tests =
-        List.concat
-          [ NormalMove.tests
-          , NormalDelete.tests
-          , Regression.tests
-          , RegexTests.tests
-          ]
+      val tests = List.concat
+        [ NormalMove.tests
+        , NormalDelete.tests
+        , NormalYank.tests
+        , Regression.tests
+        , RegexTests.tests
+        ]
       val tests = concat tests
     in
       runWithConfig [Configuration.PrintPassed false] tests
diff --git a/todo.md b/todo.md
index dcb8b20..2cf2f67 100644
--- a/todo.md
+++ b/todo.md
@@ -1,4 +1,3 @@
 # To-do list
 
-- Implement `yh` motion.
-  - Implemented. Add tests for it next (based on tests for 'dh' motion).
+- Implement `yl` motion and add tests for it.