patch 8.1.1929: no tests for text property popup window

Problem:    No tests for text property popup window.
Solution:   Add a few tests.
diff --git a/src/testdir/test_popupwin_textprop.vim b/src/testdir/test_popupwin_textprop.vim
new file mode 100644
index 0000000..26950de
--- /dev/null
+++ b/src/testdir/test_popupwin_textprop.vim
@@ -0,0 +1,54 @@
+" Tests for popup windows for text properties
+
+source check.vim
+CheckFeature textprop
+
+source screendump.vim
+CheckScreendump
+
+func Test_textprop_popup()
+  let lines =<< trim END
+	call setline(1, range(1, 100))
+	call setline(50, 'some text to work with')
+	50
+	normal zz
+	set scrolloff=0
+	call prop_type_add('popupMarker', #{highlight: 'DiffAdd'})
+	call prop_add(50, 11, #{
+		\ length: 7,
+		\ type: 'popupMarker',
+		\ })
+	let winid = popup_create('the text', #{
+	      \ pos: 'botleft', 
+	      \ textprop: 'popupMarker',
+	      \ border: [],
+	      \ padding: [0,1,0,1],
+	      \ close: 'click',
+	      \ })
+  END
+  call writefile(lines, 'XtestTextpropPopup')
+  let buf = RunVimInTerminal('-S XtestTextpropPopup', #{rows: 10})
+  call VerifyScreenDump(buf, 'Test_popup_textprop_01', {})
+
+  call term_sendkeys(buf, "zt")
+  call VerifyScreenDump(buf, 'Test_popup_textprop_02', {})
+
+  call term_sendkeys(buf, "zzIawe\<Esc>")
+  call VerifyScreenDump(buf, 'Test_popup_textprop_03', {})
+
+  call term_sendkeys(buf, "0dw")
+  call VerifyScreenDump(buf, 'Test_popup_textprop_04', {})
+
+  call term_sendkeys(buf, "Oinserted\<Esc>")
+  call VerifyScreenDump(buf, 'Test_popup_textprop_05', {})
+
+  call term_sendkeys(buf, "k2dd")
+  call VerifyScreenDump(buf, 'Test_popup_textprop_06', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XtestTextpropPopup')
+endfunc
+
+
+" vim: shiftwidth=2 sts=2