Merge pull request #323 from vimc/vimc-6820

Better handling of empty queries

Author: richfitz

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: orderly
 Title: Lightweight Reproducible Reporting
-Version: 1.5.0
+Version: 1.5.1
 Description: Order, create and store reports from R.  By defining a
     lightweight interface around the inputs and outputs of an
     analysis, a lot of the repetitive work for reproducible research

R/query_search.R

@@ -229,15 +229,26 @@ parse_query <- function(x, parameters) {
   }
   expr <- expr[[1L]]
 
-  latest <- is_call(expr, "latest")
+  test <- c("parameter", "tag")
+
+  latest <- is_call(expr, "latest") || identical(expr, as.name("latest"))
   if (latest) {
-    stopifnot(length(expr) == 2L)
-    expr <- expr[[2L]]
+    if (length(expr) == 1L) {
+      ## Special exit to make latest() work; this is done better in
+      ## outpack.
+      return(list(latest = TRUE,
+                  use = set_names(as.list(rep(FALSE, length(test))), test),
+                  expr = TRUE))
+    } else if (length(expr) == 2L) {
+      expr <- expr[[2L]]
+    } else {
+      stop(sprintf(
+        "Unexpected query '%s'; expected at most one argument to latest", x))
+    }
   }
 
   dat <- parse_query_expr(expr, parameters)
 
-  test <- c("parameter", "tag")
   use <- set_names(as.list(test %in% dat$namespace), test)
   expr <- dat$expr
   list(latest = latest, use = use, expr = expr)

tests/testthat/test-query-search.R

@@ -436,3 +436,23 @@ test_that("run query on remote", {
                    draft = "newer", remote = remote, root = root),
     "Can't use 'draft' along with 'remote'")
 })
+
+
+test_that("can cope with empty latest", {
+  dat <- prepare_orderly_query_example()
+  root <- dat$root
+  ids <- dat$ids
+  expect_equal(orderly_search("latest", "other", root = root), last(ids))
+  expect_equal(orderly_search("latest()", "other", root = root), last(ids))
+})
+
+
+test_that("meaningful error on multi-arg latest", {
+  dat <- prepare_orderly_query_example()
+  root <- dat$root
+  ids <- dat$ids
+  expect_error(
+    orderly_search("latest(a, b)", "other", root = root),
+    "Unexpected query 'latest(a, b)'; expected at most one argument to latest",
+    fixed = TRUE)
+})