Fix issue with bare google_font() passed to extra_fonts

DESCRIPTION

     here,
     knitr,
     rmarkdown,
-    testthat,
+    testthat (>= 2.1.0),
     xaringan
 VignetteBuilder: 
     knitr

R/write_extra_css.R

 }
 
 list2fonts <- function(fonts) {
+  if (inherits(fonts, "google_font")) {
+    fonts <- list(fonts)
+  }
   fonts <- purrr::map_chr(fonts, function(f) {
     if (inherits(f, "google_font")) {
       f$url

tests/testthat/test-write_extra_css.R

+import <- function(x) paste0("@import url(", x, ");")
+
+# test_that("list2fonts()", {})
+
+describe("list2fonts()", {
+
+  lato_url <- "https://fonts.googleapis.com/css?family=Lato"
+  worksans_url <- "https://fonts.googleapis.com/css?family=Work+Sans"
+
+  it("handles a list of font names", {
+    expect_equal(
+      list2fonts(list(lato_url, worksans_url)),
+      import(c(lato_url, worksans_url))
+    )
+  })
+
+  it("handles single character font name", {
+    expect_equal(list2fonts(lato_url), import(lato_url))
+  })
+
+  it("handles list of google fonts", {
+    expect_equal(
+      list2fonts(list(google_font("Lato"), google_font("Work Sans"))),
+      import(c(lato_url, worksans_url))
+    )
+  })
+
+  it("handles mix of google_font() and bare string", {
+    expect_equal(
+      list2fonts(list(google_font("Lato"), worksans_url)),
+      import(c(lato_url, worksans_url))
+    )
+  })
+
+  it("handles bare google_font()", {
+    expect_equal(
+      list2fonts(google_font("Lato")),
+      import(lato_url)
+    )
+  })
+})