cleanup(miniooni): rename kvstore2 to engine

internal/cmd/miniooni/session.go

@@ -9,6 +9,7 @@ import (
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/internal/engine"
 	"github.com/ooni/probe-cli/v3/internal/kvstore"
+	"github.com/ooni/probe-cli/v3/internal/legacy/kvstore2dir"
 	"github.com/ooni/probe-cli/v3/internal/model"
 	"github.com/ooni/probe-cli/v3/internal/runtimex"
 	"github.com/ooni/probe-cli/v3/internal/version"
@@ -27,9 +28,12 @@ func newSessionOrPanic(ctx context.Context, currentOptions *Options,
 		proxyURL = mustParseURL(currentOptions.Proxy)
 	}
 
-	kvstore2dir := filepath.Join(miniooniDir, "kvstore2")
-	kvstore, err := kvstore.NewFS(kvstore2dir)
-	runtimex.PanicOnError(err, "cannot create kvstore2 directory")
+	// We renamed kvstore2 to engine in the 3.20 development cycle
+	_ = kvstore2dir.Move(miniooniDir)
+
+	enginedir := filepath.Join(miniooniDir, "engine")
+	kvstore, err := kvstore.NewFS(enginedir)
+	runtimex.PanicOnError(err, "cannot create engine directory")
 
 	tunnelDir := filepath.Join(miniooniDir, "tunnel")
 	err = os.MkdirAll(tunnelDir, 0700)

internal/legacy/kvstore2dir/kvstore2dir.go

@@ -0,0 +1,34 @@
+// Package kvstore2dir migrates $OONI_HOME/kvstore2 to $OONI_HOME/engine. This ensures
+// that miniooni and ooniprobe use the same directory name for the engine state.
+package kvstore2dir
+
+import (
+	"os"
+	"path/filepath"
+)
+
+type statBuf interface {
+	IsDir() bool
+}
+
+func simplifiedStat(path string) (statBuf, error) {
+	return os.Stat(path)
+}
+
+var (
+	osStat   = simplifiedStat
+	osRename = os.Rename
+)
+
+// Move moves $OONI_HOME/kvstore2 to $OONI_HOME/engine, if possible.
+func Move(dir string) error {
+	kvstore2dir := filepath.Join(dir, "kvstore2")
+	if stat, err := osStat(kvstore2dir); err != nil || !stat.IsDir() {
+		return nil
+	}
+	enginedir := filepath.Join(dir, "engine")
+	if _, err := osStat(enginedir); err == nil {
+		return nil
+	}
+	return osRename(kvstore2dir, enginedir)
+}

internal/legacy/kvstore2dir/kvstore2dir_test.go

@@ -0,0 +1,102 @@
+package kvstore2dir
+
+import (
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+type booleanStatBuf bool
+
+var _ statBuf = booleanStatBuf(true)
+
+// IsDir implements statBuf.
+func (v booleanStatBuf) IsDir() bool {
+	return bool(v)
+}
+
+func TestMove(t *testing.T) {
+	// testcase is a test case implemented by this function
+	type testcase struct {
+		name     string
+		osStat   func(name string) (statBuf, error)
+		osRename func(oldpath string, newpath string) error
+		expect   error
+	}
+
+	cases := []testcase{{
+		name: "when we cannot stat kvstore2",
+		osStat: func(name string) (statBuf, error) {
+			return nil, io.EOF
+		},
+		osRename: func(oldpath string, newpath string) error {
+			panic("should not be called")
+		},
+		expect: nil,
+	}, {
+		name: "when kvstore2 is not a directory",
+		osStat: func(name string) (statBuf, error) {
+			return booleanStatBuf(false), nil
+		},
+		osRename: func(oldpath string, newpath string) error {
+			panic("should not be called")
+		},
+		expect: nil,
+	}, {
+		name: "when we can find kvstore2 as a dir and engine",
+		osStat: func(name string) (statBuf, error) {
+			if name == filepath.Join("xo", "kvstore2") {
+				return booleanStatBuf(true), nil
+			}
+			return booleanStatBuf(true), nil
+		},
+		osRename: func(oldpath string, newpath string) error {
+			panic("should not be called")
+		},
+		expect: nil,
+	}, {
+		name: "when we can find kvstore2 as a dir without engine",
+		osStat: func(name string) (statBuf, error) {
+			if name == filepath.Join("xo", "kvstore2") {
+				return booleanStatBuf(true), nil
+			}
+			return nil, io.EOF
+		},
+		osRename: func(oldpath string, newpath string) error {
+			return nil
+		},
+		expect: nil,
+	}}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			// override and restore functions
+			osStat = tc.osStat
+			osRename = tc.osRename
+			defer func() {
+				osStat = simplifiedStat
+				osRename = os.Rename
+			}()
+
+			// invoke Move
+			err := Move("xo")
+
+			// check the result
+			if !errors.Is(err, tc.expect) {
+				t.Fatal("expected", tc.expect, "got", err)
+			}
+		})
+	}
+}
+
+func TestSimplifiedStat(t *testing.T) {
+	buf, err := simplifiedStat("kvstore2dir.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if buf.IsDir() {
+		t.Fatal("expected not dir")
+	}
+}