diff --git a/src/testdir/test_excmd.vim b/src/testdir/test_excmd.vim
index 47fc267..6a7829b 100644
--- a/src/testdir/test_excmd.vim
+++ b/src/testdir/test_excmd.vim
@@ -84,18 +84,27 @@
 " Test for the :drop command
 func Test_drop_cmd()
   call writefile(['L1', 'L2'], 'Xdropfile', 'D')
+  " Test for reusing the current buffer
   enew | only
+  let expected_nr = bufnr()
   drop Xdropfile
+  call assert_equal(expected_nr, bufnr())
   call assert_equal('L2', getline(2))
   " Test for switching to an existing window
   below new
   drop Xdropfile
   call assert_equal(1, winnr())
-  " Test for splitting the current window
+  " Test for splitting the current window (set nohidden)
   enew | only
   set modified
   drop Xdropfile
   call assert_equal(2, winnr('$'))
+  " Not splitting the current window even if modified (set hidden)
+  set hidden
+  enew | only
+  set modified
+  drop Xdropfile
+  call assert_equal(1, winnr('$'))
   " Check for setting the argument list
   call assert_equal(['Xdropfile'], argv())
   enew | only!
diff --git a/src/testdir/test_tabpage.vim b/src/testdir/test_tabpage.vim
index 906fefc..46aed22 100644
--- a/src/testdir/test_tabpage.vim
+++ b/src/testdir/test_tabpage.vim
@@ -164,6 +164,74 @@
   bwipe!
   bwipe!
   call assert_equal(1, tabpagenr('$'))
+
+  call assert_equal(1, winnr('$'))
+  call assert_equal('', bufname(''))
+  call writefile(['L1', 'L2'], 'Xdropfile', 'D')
+
+  " Test for ':tab drop single-file': reuse current buffer
+  let expected_nr = bufnr()
+  tab drop Xdropfile
+  call assert_equal(1, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  bwipe!
+
+  " Test for ':tab drop single-file': not reuse modified buffer
+  set modified
+  let expected_nr = bufnr() + 1
+  tab drop Xdropfile
+  call assert_equal(2, tabpagenr())
+  call assert_equal(2, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  bwipe!
+
+  " Test for ':tab drop single-file': multiple tabs already exist
+  tab split f2
+  tab split f3
+  let expected_nr = bufnr() + 1
+  tab drop Xdropfile
+  call assert_equal(4, tabpagenr())
+  call assert_equal(4, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  %bwipe!
+
+  " Test for ':tab drop multi-files': reuse current buffer
+  let expected_nr = bufnr()
+  tab drop Xdropfile f1 f2 f3
+  call assert_equal(1, tabpagenr())
+  call assert_equal(4, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  %bwipe!
+
+  " Test for ':tab drop multi-files': not reuse modified buffer
+  set modified
+  let expected_nr = bufnr() + 1
+  tab drop Xdropfile f1 f2 f3
+  call assert_equal(2, tabpagenr())
+  call assert_equal(5, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  %bwipe!
+
+  " Test for ':tab drop multi-files': multiple tabs already exist
+  tab split f2
+  tab split f3
+  let expected_nr = bufnr() + 1
+  tab drop a b c
+  call assert_equal(4, tabpagenr())
+  call assert_equal(6, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  let expected_nr = bufnr() + 3
+  tab drop Xdropfile f1 f2 f3
+  call assert_equal(5, tabpagenr())
+  call assert_equal(8, tabpagenr('$'))
+  call assert_equal(expected_nr, bufnr())
+  call assert_equal('L2', getline(2))
+  %bwipe!
 endfunc
 
 " Test autocommands
@@ -260,14 +328,14 @@
 
   let s:li = []
   tab drop test1
-  call assert_equal(['BufLeave', 'BufEnter'], s:li)
+  call assert_equal(['BufEnter'], s:li)
 
   let s:li = []
   tab drop test2 test3
   call assert_equal([
         \ 'TabLeave', 'TabEnter', 'TabLeave', 'TabEnter',
         \ 'TabLeave', 'WinEnter', 'TabEnter', 'BufEnter',
-        \ 'TabLeave', 'WinEnter', 'TabEnter', 'BufEnter'], s:li)
+        \ 'TabLeave', 'WinEnter', 'TabEnter', 'BufEnter', 'BufEnter'], s:li)
 
   autocmd! TestTabpageGroup
   augroup! TestTabpageGroup