Fix #692, set openapi spec with file path

NEWS.md

@@ -1,6 +1,10 @@
 plumber 1.0.0.9999 Development version
 --------------------------------------------------------------------------------
 
+### New features
+
+* OpenAPI Specification can be set using a file path.
+
 ### Bug fixes
 
 * When calling `Plumber$handle()` and defining a new `PlumberEndpoint`, `...` will be checked for invalid names #677  

R/plumber.R

@@ -887,9 +887,20 @@ Plumber <- R6Class(
     #' @param api This can be
     #'   * an OpenAPI Specification formatted list object
     #'   * a function that accepts the OpenAPI Specification autogenerated by `plumber` and returns a OpenAPI Specification formatted list object.
+    #'   * a path to an OpenAPI Specification
     #'
     #'  The value returned will not be validated for OAS compatibility.
     setApiSpec = function(api = NULL) {
+      if (is.character(api) && length(api) == 1 && file.exists(api)) {
+        if (tools::file_ext(api) %in% c("yaml", "yml")) {
+          if (!requireNamespace("yaml", quietly = TRUE)) {
+            stop("yaml must be installed to read yaml format")
+          }
+          api <- yaml::read_yaml(api, eval.expr = FALSE)
+        } else {
+          api <- jsonlite::read_json(api, simplifyVector = TRUE)
+        }
+      }
       api_fun <-
         if (is.null(api)) {
           identity

tests/testthat/files/openapi.yaml

@@ -0,0 +1,15 @@
+servers:
+  - url: ''
+openapi: 3.0.3
+info:
+  description: API Description
+  title: Foo
+  version: 1.0.0
+paths:
+  /health-check:
+    get:
+      summary: ' Determine if the API is running and listening as expected'
+      responses:
+        default:
+          description: Default response.
+      parameters: []

tests/testthat/test-zzz-openapi.R

@@ -327,3 +327,8 @@ test_that("no params plumber router still produces spec when there is a func par
   spec <- pr$getApiSpec()
   expect_equal(spec$paths$`/sum`$get$parameters[[1]]$name, "num")
 })
+
+test_that("Api spec can be set using a file path", {
+  pr <- pr() %>% pr_set_api_spec(test_path("files/openapi.yaml"))
+  expect_equal(pr$getApiSpec()$paths$`/health-check`$get$summary, " Determine if the API is running and listening as expected")
+})