Add basename function to nextfile

spec/nextfile_spec.lua

@@ -1,7 +1,49 @@
-describe("nextfile", function()
+describe("basename", function()
 	local nextfile = require "nextfile"
 
-	it("returns true", function()
-		assert.is_true(nextfile.nextfile())
+	it("should return the basename of an absolute filepath", function()
+		local name = nextfile.basename("/testdir/701.txt")
+
+		assert.are.equal("701", name)
+	end)
+
+	it("should return the basename of a relative filepath", function()
+		local name = nextfile.basename("../../foo/testdir/file.mp3")
+
+		assert.are.equal("file", name)
 	end)
 end)
+
+describe("nextfile", function()
+	local prevfile = require "prevfile"
+	local nextfile = require "nextfile"
+
+	insulate("prevfile.prevfile returns nil", function()
+		prevfile.prevfile = function() return nil end
+
+		it("should call prevfile.prevfile", function()
+			spy.on(prevfile, "prevfile")
+			test_directory = "/testdir"
+
+			nextfile.nextfile(test_directory)
+
+			assert.spy(prevfile.prevfile).was_called_with(test_directory)
+		end)
+
+		it("should return nil", function()
+			local file = nextfile.nextfile("/testdir")
+
+			assert.are.equal(nil, file)
+		end)
+	end)
+
+--	insulate("prevfile.prevfile returns a numeric filename", function()
+--		prevfile.prevfile = function() return "/testdir/701.txt" end
+--
+--		it("should return the result of incrementing the filename", function()
+--			local file = nextfile.nextfile("/testdir")
+--
+--			assert.are.equal("/testdir/702.txt", file)
+--		end)
+--	end)
+end)

src/nextfile.lua

@@ -1,7 +1,15 @@
+local prevfile = require "prevfile"
+
 local nextfile = {}
 
-function nextfile.nextfile()
-	return true
+function nextfile.basename(path)
+	return path:match("^.*/(.*)%.%w*")
+
+end
+
+function nextfile.nextfile(directory)
+	prevfile.prevfile(directory)
+	return nil
 end
 
 return nextfile