adding simple test for highlighted region via with_mock.

Author: lorenzwalthert

R/addins.R

@@ -50,7 +50,7 @@ style_region <- function(text, context) {
   lines_to_style <- text[ind_to_style]
   last <- length(lines_to_style)
   lines_to_style[1] <- substring(lines_to_style[1], context$start[2])
-  start_if_on_same_line <- ifelse(context$start[1] == context$end[1], context$start[2] - 1, 0)
+  start_if_on_same_line <- ifelse(context$start[1] == context$end[1], context$start[2], 0)
   lines_to_style[last] <- substring(
     lines_to_style[last],
     1,

tests/testthat/public-api/xyzaddin/addin_region-in.R

@@ -0,0 +1 @@
+fjkdsfa 2jy+wj/ 1+1 <?+d

tests/testthat/public-api/xyzaddin/addin_region-out.R

@@ -0,0 +1 @@
+fjkdsfa 2jy+wj/ 1 + 1<?+d

tests/testthat/test-public_api.R

@@ -17,3 +17,37 @@ test_that("styler can style file", {
 })
 
 # style_active_file() must be tested manually.
+test_that("...", {
+  before_styling <- utf8::read_lines_enc(paste0(base, "/xyzaddin/addin_region-in.R"))
+  reference <- utf8::read_lines_enc(paste0(base, "/xyzaddin/addin_region-out.R"))
+  result <- expect_error(
+    testthat::with_mock(
+    find_active_context = function() {
+      context <- structure(list(
+        id = "C533793B",
+        path = paste0(base, "/xyzaddin/addin_region-in.R"),
+        contents = c("fjkdsfa 2jy+wj/ 1+1 <?+d", ""),
+        selection = structure(list(structure(list(range = structure(list(
+          start = structure(c(1, 17), .Names = c("row", "column"), class = "document_position"),
+          end = structure(c(1, 21), .Names = c("row", "column"),
+                          class = "document_position")), .Names = c("start", "end"),
+          class = "document_range"), text = "1+1 "), .Names = c("range", "text"))),
+          .Names = "", class = "document_selection")),
+        .Names = c("id", "path", "contents", "selection"), class = "document_context"
+      )
+      path <- context$path
+      start <- context$selection[[1]]$range$start
+      end <- context$selection[[1]]$range$end
+      if (all(start == end)) return()
+      if (end[2] == 1) {
+        end[1] <- end[1] - 1
+        end[2] <- 1000000L # because of range constraint in substr()
+      }
+      list(start = start, end = end, path = path)
+      },
+    style_active_region()
+  ), NA)
+  after_styling <- utf8::read_lines_enc(paste0(base, "/xyzaddin/addin_region-in.R"))
+  expect_equivalent(after_styling, reference)
+  utf8::write_lines_enc(before_styling, paste0(base, "/xyzaddin/addin_region-in.R"))
+})