Do not evaluate vignettes if cairo is not available

Author: jimhester

vignettes/converting.Rmd

@@ -14,7 +14,7 @@ knitr::opts_chunk$set(
 )
 
 should_run_benchmarks <- function(x) {
-  get("requireNamespace")("cpp11test") && asNamespace("cpp11test")$should_run_benchmarks()
+  get("requireNamespace")("cpp11test", quietly = TRUE) && asNamespace("cpp11test")$should_run_benchmarks()
 }
 ```
 
@@ -112,7 +112,7 @@ b_grow <- bench::press(.grid = grid,
 saveRDS(b_grow, "growth.Rds", version = 2)
 ```
 
-```{r, echo = FALSE, dev = "svg", fig.ext = "svg"}
+```{r, echo = FALSE, dev = "svg", fig.ext = "svg", eval = capabilities("cairo")}
 b_grow <- readRDS("growth.Rds")
 library(ggplot2)
 ggplot(b_grow, aes(x = len, y = min, color = pkg)) +

vignettes/motivations.Rmd

@@ -21,7 +21,7 @@ print_cpp <- function(filename) {
 library(cpp11)
 
 should_run_benchmarks <- function(x) {
-  get("requireNamespace")("cpp11test") && asNamespace("cpp11test")$should_run_benchmarks()
+  get("requireNamespace")("cpp11test", quietly = TRUE) && asNamespace("cpp11test")$should_run_benchmarks()
 }
 ```
 
@@ -445,7 +445,7 @@ b_release <- bench::press(.grid = grid,
 saveRDS(b_release, "release.Rds", version = 2)
 ```
 
-```{r, echo = FALSE, dev = "svg", fig.ext = "svg"}
+```{r, echo = FALSE, dev = "svg", fig.ext = "svg", eval = capabilities("cairo")}
 b_release <- readRDS("release.Rds")
 library(ggplot2)
 ggplot(b_release, aes(x = len, y = min / len, color = pkg)) +
@@ -493,7 +493,7 @@ b_grow <- bench::press(.grid = grid,
 saveRDS(b_grow, "growth.Rds", version = 2)
 ```
 
-```{r, echo = FALSE, dev = "svg", fig.ext = "svg"}
+```{r, echo = FALSE, dev = "svg", fig.ext = "svg", eval = capabilities("cairo")}
 b_grow <- readRDS("growth.Rds")
 library(ggplot2)
 ggplot(b_grow, aes(x = len, y = min, color = pkg)) +