add tests for 'f' motion

test/normal-move.sml

@@ -1951,6 +1951,78 @@ struct
         end)
     ]
 
+  val fMove = describe "move motion 'f'"
+    [ test "motion 'fw' moves cursor to first 'w' in string \"hello world\""
+        (fn _ =>
+           let
+             (* arrange *)
+             val buffer = LineGap.fromString "hello world"
+             val app = AppType.init (buffer, 0, 0)
+
+             (* act *)
+             val app = updateMany (app, "fw")
+           in
+             (* assert *)
+             Expect.isTrue (getChr app = #"w")
+           end)
+    , test "count followed by f<char> moves to count'th match" (fn _ =>
+        let
+          (* arrange *)
+          val buffer = LineGap.fromString "hello world"
+          val app = AppType.init (buffer, 0, 0)
+
+          (* act *)
+          val app = updateMany (app, "3fl")
+        in
+          (* assert *)
+          Expect.isTrue (#cursorIdx app = 9 andalso getChr app = #"l")
+        end)
+    , test
+        "'count f<char>' goes to last match when count is greater than number of chars"
+        (fn _ =>
+           let
+             (* arrange *)
+             val buffer = LineGap.fromString "hello world"
+             val app = AppType.init (buffer, 0, 0)
+
+             (* act *)
+             val app = updateMany (app, "9fl")
+           in
+             (* assert *)
+             Expect.isTrue (#cursorIdx app = 9 andalso getChr app = #"l")
+           end)
+    , test
+        "does not move cursor at all when char following 'f' is not in string"
+        (fn _ =>
+           let
+             (* arrange *)
+             val buffer = LineGap.fromString "hello world"
+             val app = AppType.init (buffer, 0, 0)
+
+             (* act *)
+             val app1 = updateMany (app, "f;")
+           in
+             (* assert *)
+             Expect.isTrue (#cursorIdx app1 = #cursorIdx app)
+           end)
+    , test "is cancellable by pressing escape" (fn _ =>
+        let
+          (* arrange *)
+          val buffer = LineGap.fromString "hello world"
+          val app = AppType.init (buffer, 0, 0)
+
+          (* act *)
+          val app1 = AppUpdate.update (app, CHAR_EVENT #"f")
+          val app2 = AppUpdate.update (app1, KEY_ESC)
+          val app3 = AppUpdate.update (app2, CHAR_EVENT #"d")
+        in
+          (* assert *)
+          Expect.isTrue
+            (#cursorIdx app1 = #cursorIdx app2
+             andalso #cursorIdx app2 = #cursorIdx app3)
+        end)
+    ]
+
   val tests = concat
     [ hMove
     , jMove
@@ -1970,5 +2042,6 @@ struct
     (* multi-char motions *)
     , tMove
     , TMove
+    , fMove
     ]
 end