Adds tests for rstudio#84, rstudio#91, rstudio#94.

tests/testthat/test_detect_mistakes.R

@@ -670,3 +670,44 @@ test_that("detect_mistakes handles weird cases", {
   )
 
 })
+
+
+test_that("detect_mistakes checks the call first", {
+
+  user <-     quote(0 + sqrt(log(2)))
+  solution <- quote(sqrt(log(2)))
+  expect_equal(
+    detect_mistakes(user, solution)
+    ,
+    wrong_value(this =  "0 + sqrt(log(2))", that = quote(sqrt(log(2))))
+    # missing_argument(this_call =  quote(sum()), that = quote(3))
+  )
+
+})
+
+test_that("detect_mistakes does not throw error for unused argument", {
+
+  a <- function(x) x
+  user <-     quote(a(1, y = 2))
+  solution <- quote(a(1))
+  expect_equal(
+    detect_mistakes(user, solution)
+    ,
+    surplus_argument(this_call = quote(a()), this = quote(2), this_name = "y")
+  )
+
+})
+
+test_that("detect_mistakes does not throw error for multiple matches of argument", {
+
+  a <- function(x, ya = 1, yb = 2) x
+  user <-     quote(a(1, y = 2))
+  solution <- quote(a(1, ya = 2))
+  expect_equal(
+    detect_mistakes(user, solution)
+    ,
+    missing_argument(this_call =  quote(a()), that = quote(2), that_name = "ya")
+  )
+
+})
+