patch 8.2.0418: code in eval.c not sufficiently covered by tests

Problem:    Code in eval.c not sufficiently covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5815)

src/testdir/test_expr.vim

@@ -73,6 +73,8 @@ func Test_strcharpart()
   call assert_equal('', strcharpart('axb', -2, 2))
 
   call assert_equal('a', strcharpart('axb', -1, 2))
+
+  call assert_equal('edit', "editor"[-10:3])
 endfunc
 
 func Test_getreg_empty_list()
@@ -476,6 +478,7 @@ func Test_function_with_funcref()
 
   call assert_fails("call function('foo()')", 'E475:')
   call assert_fails("call function('foo()')", 'foo()')
+  call assert_fails("function('')", 'E129:')
 endfunc
 
 func Test_funcref()
@@ -533,3 +536,95 @@ func Test_eval_after_if()
   if 0 | eval SetVal('a') | endif | call SetVal('b')
   call assert_equal('b', s:val)
 endfunc
+
+" Test for command-line completion of expressions
+func Test_expr_completion()
+  if !has('cmdline_compl')
+    return
+  endif
+  for cmd in [
+	\ 'let a = ',
+	\ 'const a = ',
+	\ 'if',
+	\ 'elseif',
+	\ 'while',
+	\ 'for',
+	\ 'echo',
+	\ 'echon',
+	\ 'execute',
+	\ 'echomsg',
+	\ 'echoerr',
+	\ 'call',
+	\ 'return',
+	\ 'cexpr',
+	\ 'caddexpr',
+	\ 'cgetexpr',
+	\ 'lexpr',
+	\ 'laddexpr',
+	\ 'lgetexpr']
+    call feedkeys(":" . cmd . " getl\<Tab>\<Home>\"\<CR>", 'xt')
+    call assert_equal('"' . cmd . ' getline(', getreg(':'))
+  endfor
+
+  " completion for the expression register
+  call feedkeys(":\"\<C-R>=float2\t\"\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"float2nr("', @=)
+
+  " completion for window local variables
+  let w:wvar1 = 10
+  let w:wvar2 = 10
+  call feedkeys(":echo w:wvar\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo w:wvar1 w:wvar2', @:)
+  unlet w:wvar1 w:wvar2
+
+  " completion for tab local variables
+  let t:tvar1 = 10
+  let t:tvar2 = 10
+  call feedkeys(":echo t:tvar\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo t:tvar1 t:tvar2', @:)
+  unlet t:tvar1 t:tvar2
+
+  " completion for variables
+  let g:tvar1 = 1
+  let g:tvar2 = 2
+  call feedkeys(":let g:tv\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"let g:tvar1 g:tvar2', @:)
+  " completion for variables after a ||
+  call feedkeys(":echo 1 || g:tv\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo 1 || g:tvar1 g:tvar2', @:)
+
+  " completion for options
+  call feedkeys(":echo &compat\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo &compatible', @:)
+  call feedkeys(":echo 1 && &compat\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo 1 && &compatible', @:)
+  call feedkeys(":echo &g:equala\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"echo &g:equalalways', @:)
+
+  " completion for string
+  call feedkeys(":echo \"Hello\\ World\"\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"echo \"Hello\\ World\"\<C-A>", @:)
+  call feedkeys(":echo 'Hello World'\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"echo 'Hello World'\<C-A>", @:)
+
+  " completion for command after a |
+  call feedkeys(":echo 'Hello' | cwin\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"echo 'Hello' | cwindow", @:)
+
+  " completion for environment variable
+  let $X_VIM_TEST_COMPLETE_ENV = 'foo'
+  call feedkeys(":let $X_VIM_TEST_COMPLETE_E\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_match('"let $X_VIM_TEST_COMPLETE_ENV', @:)
+  unlet $X_VIM_TEST_COMPLETE_ENV
+endfunc
+
+" Test for errors in expression evaluation
+func Test_expr_eval_error()
+  call assert_fails("let i = 'abc' . []", 'E730:')
+  call assert_fails("let l = [] + 10", 'E745:')
+  call assert_fails("let v = 10 + []", 'E745:')
+  call assert_fails("let v = 10 / []", 'E745:')
+  call assert_fails("let v = -{}", 'E728:')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab