Add wordFrequency function

Resolves #1

Change-Id: Ifba8630d09559c1c3c31343fbdc3c849dae7d4ca
diff --git a/tests/testthat/test-derekovecs.R b/tests/testthat/test-derekovecs.R
index 25778cf..7fd4980 100644
--- a/tests/testthat/test-derekovecs.R
+++ b/tests/testthat/test-derekovecs.R
@@ -32,3 +32,9 @@
   rank <- frequencyRank("Test")
   expect_true(rank %>% is.numeric & rank > 0)
 })
+
+test_that("wordFrequency works", {
+  freq <- wordFrequency("Test")
+  expect_true(freq %>% is.numeric & freq > 0)
+})
+