1 file changed, 17 insertions, 0 deletions
diff --git a/tests/extensions/harness.lua b/tests/extensions/harness.lua
index fc83a73..3df4719 100644
--- a/tests/extensions/harness.lua
+++ b/tests/extensions/harness.lua
@@ -78,6 +78,23 @@ function harness.load(script)
 	dofile(script)
 end
 
+-- Load a script with some of its own text replaced first, for checks that
+-- need the commented-out examples of its configuration switched on. Each
+-- replacement has to match exactly once, so a reworded example fails here
+-- rather than leaving the check to test the unedited configuration.
+function harness.load_with(script, replacements)
+	local file = assert(io.open(script, "rb"))
+	local source = file:read("*a")
+	file:close()
+	for _, pair in ipairs(replacements) do
+		local start = source:find(pair[1], 1, true)
+		assert(start and not source:find(pair[1], start + 1, true),
+			"expected exactly one " .. pair[1])
+		source = source:sub(1, start - 1) .. pair[2] .. source:sub(start + #pair[1])
+	end
+	assert((loadstring or load)(source, "@" .. script))()
+end
+
 local unpack_args = unpack or table.unpack
 
 -- One whole filter round trip, an open with the given arguments, a write per