Add tests

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

cmd/debug-info/main.go

@@ -1,4 +1,4 @@
-// Copyright 2021 The Parca Authors
+// Copyright (c) 2022 The Parca Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -10,6 +10,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+//
 
 package main
 
@@ -160,12 +161,11 @@ func main() {
 		})
 	case "buildid <path>":
 		g.Add(func() error {
-			buildID, err := buildid.BuildID(flags.Buildid.Path)
+			_, err := buildid.BuildID(flags.Buildid.Path)
 			if err != nil {
 				level.Error(logger).Log("msg", "failed to extract elf build ID", "err", err)
 				return err
 			}
-			fmt.Println(buildID)
 			return nil
 		}, func(error) {
 			cancel()

pkg/debuginfo/find.go

@@ -18,13 +18,20 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"path/filepath"
 
 	"github.com/go-kit/log"
 	"github.com/goburrow/cache"
 )
 
+type realfs struct{}
+
+func (f *realfs) Open(name string) (fs.File, error) { return os.Open(name) }
+
+var fileSystem fs.FS = &realfs{}
+
 // Finder finds the additional debug information on the system.
 type Finder struct {
 	logger log.Logger
@@ -73,13 +80,16 @@ func (f *Finder) Find(ctx context.Context, buildID, root string) (string, error)
 }
 
 func find(buildID, root string) (string, error) {
+	if len(buildID) < 2 {
+		return "", errors.New("invalid build ID")
+	}
 	// Debian: /usr/lib/debug/.build-id/f9/02f8a561c3abdb9c8d8c859d4243bd8c3f928f.debug
 	// -- apt install <package>-dbg
 	// Fedora: /usr/lib/debug/.build-id/da/40581445b62eff074d67fae906792cb26e8d54.debug
 	// -- dnf --enablerepo=fedora-debuginfo --enablerepo=updates-debuginfo install <package>-debuginfo
 	// Arch: https://wiki.archlinux.org/title/Debugging/Getting_traces
-	file := filepath.Join(root, "/usr/lib/debug", ".build-id", buildID[:2], buildID[2:])
-	_, err := os.Stat(file)
+	file := filepath.Join(root, "/usr/lib/debug", ".build-id", buildID[:2], buildID[2:]) + ".debug"
+	_, err := fs.Stat(fileSystem, file)
 	if err == nil {
 		return file, nil
 	}

pkg/debuginfo/find_test.go

@@ -0,0 +1,74 @@
+// Copyright (c) 2022 The Parca Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package debuginfo
+
+import (
+	"testing"
+
+	"github.com/parca-dev/parca-agent/pkg/testutil"
+)
+
+func Test_find(t *testing.T) {
+	oldFs := fileSystem
+	mfs := testutil.NewFakeFS(map[string][]byte{
+		"/proc/124/root/usr/lib/debug/.build-id/d1/b25b63b3edc63832fd885e4b997f8a463ea573.debug": []byte("whatever"),
+	})
+	fileSystem = mfs
+	t.Cleanup(func() {
+		fileSystem = oldFs
+	})
+
+	type args struct {
+		buildID string
+		root    string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "empty",
+			args: args{
+				buildID: "",
+				root:    "",
+			},
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name: "valid",
+			args: args{
+				buildID: "d1b25b63b3edc63832fd885e4b997f8a463ea573",
+				root:    "/proc/124/root",
+			},
+			want:    "/proc/124/root/usr/lib/debug/.build-id/d1/b25b63b3edc63832fd885e4b997f8a463ea573.debug",
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := find(tt.args.buildID, tt.args.root)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("find() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("find() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}