From 94a9e1f48c73f4634a1f088522c79e9810e5fb27 Mon Sep 17 00:00:00 2001
From: jolheiser <john.olheiser@gmail.com>
Date: Sun, 9 May 2021 04:02:16 +0000
Subject: [PATCH] Add ReadFile, interface guard, and drone CI (#2)

Reviewed-on: https://git.jojodev.com/jolheiser/overlay/pulls/2
Co-authored-by: jolheiser <john.olheiser@gmail.com>
Co-committed-by: jolheiser <john.olheiser@gmail.com>
---
 .drone.yml      | 17 +++++++++++++++++
 README.md       |  3 +++
 overlay.go      | 21 +++++++++++++++++++++
 overlay_test.go |  3 +--
 4 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 .drone.yml

diff --git a/.drone.yml b/.drone.yml
new file mode 100644
index 0000000..7d4d631
--- /dev/null
+++ b/.drone.yml
@@ -0,0 +1,17 @@
+---
+kind: pipeline
+name: compliance
+trigger:
+  event:
+    - pull_request
+steps:
+  - name: build
+    pull: always
+    image: golang:1.16
+    commands:
+      - make test
+  - name: check
+    pull: always
+    image: golang:1.16
+    commands:
+      - make vet
\ No newline at end of file
diff --git a/README.md b/README.md
index 2f32c46..4f0db5a 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,7 @@
 # Overlay
+
+[![Build Status](https://ci.jojodev.com/api/badges/jolheiser/overlay/status.svg?ref=refs/heads/main)](https://ci.jojodev.com/jolheiser/overlay)
+
 Overlay File System
 
 Overlay is an easy way to implement a file system in such a way that
diff --git a/overlay.go b/overlay.go
index 8dab55d..512bf1c 100644
--- a/overlay.go
+++ b/overlay.go
@@ -6,6 +6,10 @@ import (
 	"path"
 )
 
+// Interface guard
+// fs.ReadFileFS also fulfills fs.FS
+var _ fs.ReadFileFS = (*FS)(nil)
+
 // FS is an overlay File System
 type FS struct {
 	fs      fs.FS
@@ -39,6 +43,14 @@ func (f *FS) Open(name string) (fs.File, error) {
 	return f.fs.Open(name)
 }
 
+// ReadFile reads a file, preferring disk
+func (f *FS) ReadFile(name string) ([]byte, error) {
+	if f.exists(name) {
+		return os.ReadFile(f.apn(name))
+	}
+	return fs.ReadFile(f.fs, name)
+}
+
 // ReadDir reads []fs.DirEntry
 // This method will prefer EMBEDDED, because that is the "real" FS for overlay
 func (f *FS) ReadDir(name string) ([]fs.DirEntry, error) {
@@ -66,6 +78,15 @@ func New(root string, fs fs.FS, opts ...Option) (*FS, error) {
 	return x, nil
 }
 
+// MustNew returns New and panics on error
+func MustNew(root string, fs fs.FS, opts ...Option) *FS {
+	f, err := New(root, fs, opts...)
+	if err != nil {
+		panic(err)
+	}
+	return f
+}
+
 // WithSub sets a fs.Sub for an FS
 func WithSub(sub string) Option {
 	return func(x *FS) (err error) {
diff --git a/overlay_test.go b/overlay_test.go
index 07ec8d2..80ce918 100644
--- a/overlay_test.go
+++ b/overlay_test.go
@@ -2,7 +2,6 @@ package overlay
 
 import (
 	"embed"
-	"io"
 	"io/fs"
 	"os"
 	"strings"
@@ -49,7 +48,7 @@ func TestOverlay(t *testing.T) {
 			}
 			defer fi.Close()
 
-			contents, err := io.ReadAll(fi)
+			contents, err := x.ReadFile(tc.File)
 			if err != nil {
 				t.Log(err)
 				t.FailNow()