6 files changed, 77 insertions, 6 deletions
diff --git a/Taskfile.yml b/Taskfile.yml
index 7a7ec41..a8347d2 100644
--- a/Taskfile.yml
+++ b/Taskfile.yml
@@ -14,7 +14,7 @@ tasks:
       - go test -v ./... 
   vet:
     cmds:
-      - go vet **/*.go
+      - go vet ./...
   lint:
     cmds:
       - golangci-lint run
diff --git a/internal/types/entry.go b/internal/types/entry.go
index b4a05e4..c2ccb82 100644
--- a/internal/types/entry.go
+++ b/internal/types/entry.go
@@ -168,7 +168,7 @@ func (e Entry) SaveFile(filePath string) error {
 		return err
 	}
 
-	return e.vfs.SaveFile(filePath, jsonStr)
+	return e.vfs.WriteFile(filePath, jsonStr)
 }
 
 func (e Entry) String() string {
diff --git a/internal/vfs/memoryfs.go b/internal/vfs/memoryfs.go
index 22b1611..6250e39 100644
--- a/internal/vfs/memoryfs.go
+++ b/internal/vfs/memoryfs.go
@@ -5,6 +5,7 @@ import (
 	"strings"
 )
 
+// VFS implementaion especially for unit testing.
 type MemoryFS map[string][]byte
 
 func (fs MemoryFS) ReadFile(filePath string) ([]byte, error) {
@@ -14,7 +15,7 @@ func (fs MemoryFS) ReadFile(filePath string) ([]byte, error) {
 	return []byte{}, fmt.Errorf("no such file path: %s", filePath)
 }
 
-func (fs MemoryFS) SaveFile(filePath string, bytes []byte) error {
+func (fs MemoryFS) WriteFile(filePath string, bytes []byte) error {
 	fs[filePath] = bytes
 	return nil
 }
@@ -23,7 +24,7 @@ func (fs MemoryFS) FindFiles(dataDir, suffix string) ([]string, error) {
 	var filePaths []string
 
 	for filePath := range fs {
-		if !strings.HasSuffix(filePath, suffix) {
+		if !strings.HasPrefix(filePath, dataDir) || !strings.HasSuffix(filePath, suffix) {
 			continue
 		}
 		filePaths = append(filePaths, filePath)
diff --git a/internal/vfs/memoryfs_test.go b/internal/vfs/memoryfs_test.go
new file mode 100644
index 0000000..46607e0
--- /dev/null
+++ b/internal/vfs/memoryfs_test.go
@@ -0,0 +1,70 @@
+package vfs
+
+import (
+	"slices"
+	"strings"
+	"testing"
+)
+
+func TestMemoryFS(t *testing.T) {
+	t.Parallel()
+	var vfs VFS = make(MemoryFS)
+
+	writeFiles := map[string]string{
+		"/data/dir/foo.json":        "hello world",
+		"/data/dir/subdir/bar.json": "hello solar system",
+		"/data/dir/subdir/baz.json": "hello universe",
+		"/data/dir/subdir/bay.txt":  "hello bar keeper",
+	}
+
+	for path, content := range writeFiles {
+		bytes := []byte(content)
+		_ = vfs.WriteFile(path, bytes)
+	}
+
+	t.Run("files are there", func(t *testing.T) {
+		testFilesAreThere(t, vfs, writeFiles)
+	})
+
+	t.Run("find json files", func(t *testing.T) {
+		testFindFiles(t, vfs, writeFiles, "/data/dir/subdir", ".json", 2)
+	})
+}
+
+func testFindFiles(t *testing.T, vfs VFS, writeFiles map[string]string, dataDir, suffix string, count int) {
+	filePaths, err := vfs.FindFiles(dataDir, suffix)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	if len(filePaths) != count {
+		t.Error("expected", count, "json files, but got", filePaths)
+		return
+	}
+
+	for filePath := range writeFiles {
+		if !strings.HasPrefix(filePath, dataDir) || !strings.HasSuffix(filePath, suffix) {
+			continue
+		}
+
+		if !slices.Contains(filePaths, filePath) {
+			t.Error("expected file", filePath, "to be there, but it isn't in", filePaths)
+			return
+		}
+	}
+}
+
+func testFilesAreThere(t *testing.T, vfs VFS, writeFiles map[string]string) {
+	for path, content := range writeFiles {
+		bytes, err := vfs.ReadFile(path)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if content != string(bytes) {
+			t.Error("expected", content, "in file", path, "but got", string(bytes))
+			return
+		}
+	}
+}
diff --git a/internal/vfs/realfs.go b/internal/vfs/realfs.go
index 8b9c9de..afd3eb1 100644
--- a/internal/vfs/realfs.go
+++ b/internal/vfs/realfs.go
@@ -13,7 +13,7 @@ func (RealFS) ReadFile(filePath string) ([]byte, error) {
 	return os.ReadFile(filePath)
 }
 
-func (RealFS) SaveFile(filePath string, bytes []byte) error {
+func (RealFS) WriteFile(filePath string, bytes []byte) error {
 	dir := filepath.Dir(filePath)
 	if _, err := os.Stat(dir); os.IsNotExist(err) {
 		if err := os.MkdirAll(dir, 0755); err != nil {
diff --git a/internal/vfs/vfs.go b/internal/vfs/vfs.go
index 0297ff9..c31a458 100644
--- a/internal/vfs/vfs.go
+++ b/internal/vfs/vfs.go
@@ -3,6 +3,6 @@ package vfs
 // virtual file system - useful for testing as well
 type VFS interface {
 	ReadFile(name string) ([]byte, error)
-	SaveFile(filePath string, bytes []byte) error
+	WriteFile(filePath string, bytes []byte) error
 	FindFiles(dataPath, suffix string) ([]string, error)
 }