x = c(-0.2, -0.05, 0.1, 0.15, 0.2)
wilcox.test(x)


    Wilcoxon signed rank test with continuity correction

data:  x
V = 9.5, p-value = 0.6845
alternative hypothesis: true location is not equal to 0

Warning message:
In wilcox.test.default(x) : cannot compute exact p-value with ties

x = c(0.1, 0.3, 0.4, 0.5, 0.8)
wilcox.test(x, alt="gr")$p.val
[1] 0.03125

set.seed(617)
pv =  replicate( 10^5,
       wilcox.test(round(runif(15, -.4, 1),1), alt="g")$p.val )
There were 50 or more warnings (use warnings() to see the first 50)
mean(pv <= .05)
[1] 0.81138

set.seed(617)
x = round(runif(15, -.4, 1),1)
sort(x)
 [1] -0.4 -0.3 -0.1 -0.1  0.1  0.2  0.3  0.5  0.7
[10]  0.7  0.8  0.8  0.8  1.0  1.0

wilcox.test(x, alt="g")

        Wilcoxon signed rank test with continuity correction
data:  x
V = 103.5, p-value = 0.007189
alternative hypothesis: true location is greater than 0

Warning message:
In wilcox.test.default(x, alt = "g") :
  cannot compute exact p-value with ties