Fix filecount plugin size tests (#6038)

plugins/inputs/filecount/filesystem_helpers_test.go

@@ -0,0 +1,90 @@
+package filecount
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMTime(t *testing.T) {
+	//this is the time our foo file should have
+	mtime := time.Date(2015, time.December, 14, 18, 25, 5, 0, time.UTC)
+
+	fs := getTestFileSystem()
+	fileInfo, err := fs.Stat("/testdata/foo")
+	require.Nil(t, err)
+	require.Equal(t, mtime, fileInfo.ModTime())
+}
+
+func TestSize(t *testing.T) {
+	//this is the time our foo file should have
+	size := int64(4096)
+	fs := getTestFileSystem()
+	fileInfo, err := fs.Stat("/testdata")
+	require.Nil(t, err)
+	require.Equal(t, size, fileInfo.Size())
+}
+
+func TestIsDir(t *testing.T) {
+	//this is the time our foo file should have
+	dir := true
+	fs := getTestFileSystem()
+	fileInfo, err := fs.Stat("/testdata")
+	require.Nil(t, err)
+	require.Equal(t, dir, fileInfo.IsDir())
+}
+
+func TestRealFS(t *testing.T) {
+	//test that the default (non-test) empty FS causes expected behaviour
+	var fs fileSystem = osFS{}
+	//the following file exists on disk - and not in our fake fs
+	fileInfo, err := fs.Stat(getTestdataDir() + "/qux")
+	require.Nil(t, err)
+	require.Equal(t, false, fileInfo.IsDir())
+	require.Equal(t, int64(446), fileInfo.Size())
+
+	// now swap out real, for fake filesystem
+	fs = getTestFileSystem()
+	// now, the same test as above will return an error as the file doesn't exist in our fake fs
+	expectedError := "Stat " + getTestdataDir() + "/qux: No such file or directory"
+	fileInfo, err = fs.Stat(getTestdataDir() + "/qux")
+	require.Equal(t, expectedError, err.Error())
+	// and verify that what we DO expect to find, we do
+	fileInfo, err = fs.Stat("/testdata/foo")
+	require.Nil(t, err)
+}
+
+func getTestFileSystem() fakeFileSystem {
+	/*
+		create our desired "filesystem" object, complete with an internal map allowing our funcs to return meta data as requested
+
+		type FileInfo interface {
+			Name() string       // base name of the file
+			Size() int64        // length in bytes of file
+			Mode() FileMode     // file mode bits
+			ModTime() time.Time // modification time
+			IsDir() bool        // returns bool indicating if a Dir or not
+			Sys() interface{}   // underlying data source. always nil (in this case)
+		}
+
+	*/
+
+	mtime := time.Date(2015, time.December, 14, 18, 25, 5, 0, time.UTC)
+
+	// set file permisions
+	var fmask uint32 = 0666
+	var dmask uint32 = 0666
+
+	// set directory bit
+	dmask |= (1 << uint(32-1))
+
+	fileList := map[string]fakeFileInfo{
+		"/testdata":     {name: "testdata", size: int64(4096), filemode: uint32(dmask), modtime: mtime, isdir: true},
+		"/testdata/foo": {name: "foo", filemode: uint32(fmask), modtime: mtime},
+	}
+
+	fs := fakeFileSystem{files: fileList}
+	return fs
+
+}