Add tests for lsp#utils#byteindex()

test/.themisrc

@@ -1,2 +1,3 @@
+set encoding=utf-8
 call themis#option('recursive', 1)
 call themis#helper('command').with(themis#helper('assert'))

test/lsp/utils.vimspec

@@ -81,4 +81,32 @@ Describe lsp#utils
             endfor
         End
     End
+
+    Describe lsp#utils#byteindex
+        It should return the byte-index from the given character-index on a buffer
+            call setline(1, ['a β c', 'δ', ''])
+            Assert lsp#utils#byteindex('%', 1, 0) == 1
+            Assert lsp#utils#byteindex('%', 1, 1) == 2
+            Assert lsp#utils#byteindex('%', 1, 2) == 3
+            Assert lsp#utils#byteindex('%', 1, 3) == 5
+            Assert lsp#utils#byteindex('%', 1, 4) == 6
+            Assert lsp#utils#byteindex('%', 1, 5) == 7
+            Assert lsp#utils#byteindex('%', 2, 0) == 1
+            Assert lsp#utils#byteindex('%', 2, 1) == 3
+            Assert lsp#utils#byteindex('%', 3, 0) == 1
+            %delete
+        End
+
+        It should return the byte-index from the given character-index in an unloaded file
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 0) == 1
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 1) == 2
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 2) == 3
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 3) == 5
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 4) == 6
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 1, 5) == 7
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 2, 0) == 1
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 2, 1) == 3
+            Assert lsp#utils#byteindex('./test/testfiles/multibyte.txt', 3, 0) == 1
+        End
+    End
 End

test/testfiles/multibyte.txt

@@ -0,0 +1,3 @@
+a β c
+δ
+