Search for config files in any parent directories

Rather than just looking for a package directory, this allows you to use
one .lintr configuration for all of your projects by placing it in a
common parent directory.

It should also fix discovery of lintr configuation in tests as well (I
believe)

Fixes #238
Fixes #345

NEWS.md

@@ -1,4 +1,5 @@
 # lintr 1.0.3.9000 # 
+* lintr now looks up its configuration in any parent directories as well as the package directory (#238, #345)
 * `object_usage_linter()` has been changed to better detect lexical scoping of global variables (#27, #336, #91, #382)
 * `object_usage_linter()` now respects `utils::globalVariables()`, so it can be used to avoid false positive warnings due to non-standard evaluation (#352)
 * `seq_linter` is now one of the default linters (#316).

R/lint.R

@@ -256,6 +256,27 @@ find_package <- function(path = getwd()) {
   normalizePath(prev_path)
 }
 
+is_root <- function(path) {
+  identical(path, dirname(path))
+}
+
+has_config <- function(path, config) {
+  file.exists(file.path(path, config))
+}
+
+find_config2 <- function(path) {
+  config <- basename(getOption("lintr.linter_file"))
+  path <- normalizePath(path, mustWork = FALSE)
+
+  while (!has_config(path, config)) {
+    path <- dirname(path)
+    if (is_root(path)) {
+      return(character())
+    }
+  }
+  return(file.path(path, config))
+}
+
 pkg_name <- function(path = find_package()) {
   if (is.null(path)) {
     return(NULL)

R/settings.R

@@ -78,9 +78,8 @@ find_config <- function(filename) {
     return(linter_config)
   }
 
-  ## next check for a file in the project directory
-  project <- find_package(path)
-  linter_config <- file.path(project, linter_file)
+  ## next check for a file higher directories
+  linter_config <- find_config2(path)
   if (isTRUE(file.exists(linter_config))) {
     return(linter_config)
   }