Minor update in workflow: Test first, then Check

README

@@ -20,8 +20,8 @@ Some useful keyboard shortcuts for package authoring:
 
   Build and Reload Package:  'Cmd + Shift + B'
   Update Documentation:      'Cmd + Shift + D' or devtools::document()
-  Check Package:             'Cmd + Shift + E'
   Test Package:              'Cmd + Shift + T'
+  Check Package:             'Cmd + Shift + E'
 -----------------------------------------------
 
 Run before every commit:

tests/testthat/testDummy.R

@@ -0,0 +1,55 @@
+# testDummy.R
+#
+# Dummy tests as a template for unit testing in test-driven development
+# for the rete project.
+context("<Dummy tests>")
+
+# for demonstration only - remove!
+dummyF <- function(a) {
+    if (is.null(a) || length(a) == 0 || !is.numeric(a)) { stop() }
+    attr(a, "date") <- Sys.Date()
+    return(a * a)
+}
+
+test_that("parameter errors are correctly handled", {
+    # Try each parameter missing in turn
+    # Try parameters out of expected bounds
+    # Try NULL and length-zero parameters: be sure none lead to an erroneous
+    #    one-time execution of any loop
+    expect_equal(as.numeric(dummyF(2)), 4)
+    expect_equal(as.numeric(dummyF(-1/3)), 1/9)
+    expect_equal(as.numeric(dummyF(-1/0)), Inf)
+    expect_error(dummyF())
+    expect_error(dummyF(TRUE))
+    expect_error(dummyF("2"))
+    expect_error(dummyF(NULL))
+    expect_error(dummyF(numeric()))
+})
+
+
+test_that("a sane input gives an expected output", {
+    # Provide small input data, provide small output data.
+    #   (Note that the output needs to be independently verifiably correct.
+    #    Don't run an erroneous function, and then test against the erroneous
+    #    output you received when you ran your function for the first time.)
+    # Try this with important variations of parameters (reasonable, not
+    #    combinatorially exhaustive).
+    # Cover your code.
+    expect_equal(as.numeric(dummyF(2)), 4)
+    expect_equal(attr(dummyF(2), "date"), Sys.Date())
+    expect_equal(dummyF(dummyF(2)), dummyF(4))
+})
+
+
+test_that("a corrupt input does not lead to corrupted output", {
+    # Try: - spurious characters in numeric columns ("N/A", ...).
+    #      - extra tabs at line-end
+    #      - comments before headers
+    #      - truncated file (incomplete last line)
+    # Again: make absolutely sure be you never have an erroneous
+    #        one-time execution of a loop
+    expect_error(dummyF(NA))
+})
+
+
+# [END]