How can I write a test function like this? - r

Question

How can I write a function to check cases(x,y) by the two
tests:
One
if y==rank(y)
Two
xranks <- rank(x)
yranks <- rank(y)
meanx <- mean(xranks)
meany <- mean(yranks)
covariance.term <- cov(xranks-meanx,y-meany)
sd.x <- sd(xranks)
sd.y <- sd(yranks)
if -1<= covariance.term/(sd.x*sd.y) <=1
and should return TRUE if both tests are passed, or FALSE, with warnings about which tests failed.

Answer 1

The following should do what you want, but as you didn't provide test cases, I am not sure if it works.
check.xy <- function(x,y) {
xranks <- rank(x)
yranks <- rank(y)
meanx <- mean(xranks)
meany <- mean(yranks)
covariance.term <- cov(xranks-meanx,y-meany)
sd.x <- sd(xranks)
sd.y <- sd(yranks)
testA <- all(y == rank(y))
testB <- all(-1 <= covariance.term/(sd.x*sd.y) & covariance.term/(sd.x*sd.y) <=1)
if (testA & testB) return(TRUE)
else if (testA) warning("test two failed")
else if (testB) warning("test one failed")
else warning("tests one and two failed")
FALSE
}

Answer 2

I think to define each test in a single function, especially that we want warnings about which tests failed.
The 2 tests share the same environment, that why I defined them as a nested functions.
multitest <- function(x,y){
test.covariance <- function(){
xranks <- rank(x)
yranks <- rank(y)
meanx <- mean(xranks)
meany <- mean(yranks)
covariance.term <- cov(xranks-meanx,y-meany)
sd.x <- sd(xranks)
sd.y <- sd(yranks)
cov.norm <- covariance.term/(sd.x*sd.y)
res <- cov.norm > -1 && cov.norm < 1
if(is.na(res) || res > 0) warning('test covariance range failed',.call = FALSE)
res
}
test.rank <- function(){
res <- all(y==rank(y))
if(!res) warning('test rank failed')
res
}
res <- test.covariance() && test.rank()
!is.na(res)
}
some tests :
success
x <- 1:10
y <- 1:10
multitest(x,y)
[1] TRUE
failure rank
x <- rnorm(10)
y <- rnorm(10)
multitest(x,y)
[1] FALSE
Warning message:
In test.rank() : test rank failed
failure covariance
x <- rep(10,10)
y <- 1:10
multitest(x,y)
[1] FALSE
Warning message:
In test.covariance() : test covariance range failed