add tests for 'df<char>' motion, uncover bug found by test where new match was not recognised after deletion if match involved last character in buffer, and fix that bug by checking (in fcore/search-list/search-list.sm) if we are at a dead state before we check if we are in the last index of the buffer

shf/test/normal-delete-tests.sml

@@ -6296,6 +6296,153 @@ struct
           Expect.isTrue
             (actualString = expectedString andalso cursorIdx = expectedCursorIdx)
         end)
+    , test "has same searchList when deleting after all matches" (fn _ =>
+        let
+          (* arrange *)
+          val originalIdx = 9
+          val originalString = "hello world again\n"
+
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, originalIdx)
+
+          val app = TestUtils.updateMany (app, "/o")
+          val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+          (* act *)
+          val newApp = TestUtils.updateMany (app, "dfn")
+        in
+          (* assert *)
+          Expect.isTrue (#searchList app = #searchList newApp)
+        end)
+    , test "decrements search list when we delete text section preceding match"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalIdx = 0
+             val originalString = "hello\nworld\n"
+
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, originalIdx)
+
+             val app = TestUtils.updateMany (app, "/world")
+             val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+             (* act *)
+             val newApp = TestUtils.updateMany (app, "dfl")
+
+             (* assert *)
+             val oldSearchList = #searchList app
+             val oldSearchList = PersistentVector.toList oldSearchList
+
+             val newSearchList = #searchList newApp
+             val newSearchList = PersistentVector.toList newSearchList
+
+             val expectedOldSearchList = [{start = 6, finish = 10}]
+             val expectedNewSearchList = [{start = 3, finish = 7}]
+
+             val assertion =
+               oldSearchList = expectedOldSearchList
+               andalso newSearchList = expectedNewSearchList
+           in
+             Expect.isTrue assertion
+           end)
+    , test "recognises new match when there is a match after deletion" (fn _ =>
+        let
+          (* arrange *)
+          val originalIdx = 5
+          val originalString = "hello again world\n"
+
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, originalIdx)
+
+          val app = TestUtils.updateMany (app, "/hello world")
+          val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+          (* act *)
+          val newApp = TestUtils.updateMany (app, "dfn")
+
+          (* assert *)
+          val oldSearchList = #searchList app
+          val oldSearchList = PersistentVector.toList oldSearchList
+          val newSearchList = #searchList newApp
+          val newSearchList = PersistentVector.toList newSearchList
+
+          val expectedOldSearchList = []
+          val expectedNewSearchList = [{start = 0, finish = 10}]
+
+          val assertion =
+            oldSearchList = expectedOldSearchList
+            andalso newSearchList = expectedNewSearchList
+        in
+          Expect.isTrue assertion
+        end)
+    , test
+        "extends existing match when existing match should extend after deletion"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalIdx = 5
+             val originalString = "hello world\n"
+
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, originalIdx)
+
+             val app = TestUtils.updateMany (app, "/o+")
+             val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+             (* act *)
+             val newApp = TestUtils.updateMany (app, "dfw")
+
+             (* assert *)
+             val oldSearchList = #searchList app
+             val oldSearchList = PersistentVector.toList oldSearchList
+
+             val newSearchList = #searchList newApp
+             val newSearchList = PersistentVector.toList newSearchList
+
+             val expectedOldSearchList =
+               [{start = 4, finish = 4}, {start = 7, finish = 7}]
+             val expectedNewSearchList = [{start = 4, finish = 5}]
+
+             val assertion =
+               oldSearchList = expectedOldSearchList
+               andalso newSearchList = expectedNewSearchList
+           in
+             Expect.isTrue assertion
+           end)
+    , test
+        "deletes match in search list \
+        \when match no longer exists in buffer after deletion"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalIdx = 3
+             val originalString = "hello world test again\n"
+
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, originalIdx)
+
+             val app = TestUtils.updateMany (app, "/world")
+             val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+             (* act *)
+             val newApp = TestUtils.updateMany (app, "dft")
+
+             (* assert *)
+             val oldSearchList = #searchList app
+             val oldSearchList = PersistentVector.toList oldSearchList
+             val newSearchList = #searchList newApp
+             val newSearchList = PersistentVector.toList newSearchList
+
+             val expectedOldSearchList = [{start = 6, finish = 10}]
+             val expectedNewSearchList = []
+
+             val assertion =
+               oldSearchList = expectedOldSearchList
+               andalso newSearchList = expectedNewSearchList
+           in
+             Expect.isTrue assertion
+           end)
     ]
 
   val dtDelete = describe "delete motion 'dt<char>'"