fix a minor defect in fakeFile Readdir() and unit tests (#53)

internal/db/migrations/driver.go

@@ -21,18 +21,7 @@ type migrationDriver struct {
 
 // Open returns the given "file"
 func (m *migrationDriver) Open(name string) (http.File, error) {
-	var ff *fakeFile
-	switch m.dialect {
-	case "postgres":
-		ff = postgresMigrations[name]
-	}
-	if ff == nil {
-		return nil, os.ErrNotExist
-	}
-	ff.name = strings.TrimPrefix(name, "migrations/")
-	ff.reader = bytes.NewReader(ff.bytes)
-	ff.dialect = m.dialect
-	return ff, nil
+	return newFakeFile(m.dialect, name)
 }
 
 // NewMigrationSource creates a source.Driver using httpfs with the given dialect
@@ -53,6 +42,20 @@ type fakeFile struct {
 	dialect string
 }
 
+func newFakeFile(dialect string, name string) (*fakeFile, error) {
+	var ff *fakeFile
+	switch dialect {
+	case "postgres":
+		ff = postgresMigrations[name]
+	}
+	if ff == nil {
+		return nil, os.ErrNotExist
+	}
+	ff.name = strings.TrimPrefix(name, "migrations/")
+	ff.reader = bytes.NewReader(ff.bytes)
+	ff.dialect = dialect
+	return ff, nil
+}
 func (f *fakeFile) Read(p []byte) (n int, err error) {
 	return f.reader.Read(p)
 }
@@ -84,7 +87,7 @@ func (f *fakeFile) Readdir(count int) ([]os.FileInfo, error) {
 
 	// Create the slice of fileinfo objects to return
 	ret := make([]os.FileInfo, 0, len(migrationsMap))
-	for _, v := range keys {
+	for i, v := range keys {
 		// We need "migrations" in the map for the initial Open call but we
 		// should not return it as part of the "directory"'s "files".
 		if v == "migrations" {
@@ -95,6 +98,9 @@ func (f *fakeFile) Readdir(count int) ([]os.FileInfo, error) {
 			return nil, err
 		}
 		ret = append(ret, stat)
+		if count > 0 && count == i {
+			break
+		}
 	}
 	return ret, nil
 }

internal/db/migrations/driver_test.go

@@ -0,0 +1,177 @@
+package migrations
+
+import (
+	"os"
+	"reflect"
+	"testing"
+
+	"github.com/golang-migrate/migrate/v4/source"
+	"github.com/golang-migrate/migrate/v4/source/httpfs"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewMigrationSource(t *testing.T) {
+	type args struct {
+		dialect string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    source.Driver
+		wantErr bool
+	}{
+		{
+			name: "postgres",
+			args: args{dialect: "postgres"},
+			want: func() source.Driver {
+				d, err := httpfs.New(&migrationDriver{"postgres"}, "migrations")
+				if err != nil {
+					t.Errorf("NewMigrationSource() error creating httpfs = %w", err)
+				}
+				return d
+			}(),
+			wantErr: false,
+		},
+		{
+			name:    "no-dialect",
+			args:    args{dialect: ""},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "bad-dialect",
+			args:    args{dialect: "rainbows-and-unicorns-db"},
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := NewMigrationSource(tt.args.dialect)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("NewMigrationSource() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("NewMigrationSource() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_migrationDriver_Open(t *testing.T) {
+	type args struct {
+		name string
+	}
+	tests := []struct {
+		name    string
+		dialect string
+		args    args
+		wantErr bool
+	}{
+		{
+			name:    "valid-file",
+			dialect: "postgres",
+			args:    args{name: "migrations/01_domain_types.up.sql"},
+			wantErr: false,
+		},
+		{
+			name:    "bad-file",
+			dialect: "postgres",
+			args:    args{name: "migrations/unicorns-and-rainbows.up.sql"},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			m := &migrationDriver{
+				dialect: tt.dialect,
+			}
+			_, err := m.Open(tt.args.name)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("migrationDriver.Open() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+		})
+	}
+}
+
+func Test_fakeFile_Read(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("valid", func(t *testing.T) {
+		ff, err := newFakeFile("postgres", "migrations/01_domain_types.up.sql")
+		assert.Nil(err)
+		buf := make([]byte, len(ff.bytes))
+		n, err := ff.Read(buf)
+		assert.Nil(err)
+		assert.Equal(len(buf), n)
+	})
+}
+
+func Test_fakeFile_Seek(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("valid", func(t *testing.T) {
+		ff, err := newFakeFile("postgres", "migrations/01_domain_types.up.sql")
+		assert.Nil(err)
+		buf := make([]byte, len(ff.bytes))
+		n, err := ff.Seek(10, 0)
+		assert.Nil(err)
+		assert.Equal(int64(10), n)
+
+		n2, err := ff.Read(buf)
+		assert.Nil(err)
+		assert.Equal(len(ff.bytes)-10, n2)
+	})
+}
+
+func Test_fakeFile_Close(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("valid", func(t *testing.T) {
+		m := &migrationDriver{
+			dialect: "postgres",
+		}
+		f, err := m.Open("migrations/01_domain_types.up.sql")
+		assert.Nil(err)
+		err = f.Close()
+		assert.Nil(err)
+	})
+}
+
+func Test_fakeFile_Stat(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("valid", func(t *testing.T) {
+		name := "migrations/01_domain_types.up.sql"
+		ff, err := newFakeFile("postgres", name)
+		assert.Nil(err)
+		info, err := ff.Stat()
+		assert.Nil(err)
+		assert.Equal(ff.name, info.Name())
+		assert.Equal(int64(len(ff.bytes)), info.Size())
+		assert.Equal(os.ModePerm, info.Mode())
+		assert.Equal(false, info.IsDir())
+		assert.Equal(nil, info.Sys())
+	})
+}
+
+func Test_fakeFile_Readdir(t *testing.T) {
+	assert := assert.New(t)
+	t.Run("valid", func(t *testing.T) {
+		name := "migrations/01_domain_types.up.sql"
+		ff, err := newFakeFile("postgres", name)
+		assert.Nil(err)
+		info, err := ff.Readdir(0)
+		assert.Nil(err)
+		assert.True(info != nil)
+
+		info, err = ff.Readdir(1)
+		assert.Nil(err)
+		assert.True(info != nil)
+		assert.Equal(1, len(info))
+
+		info, err = ff.Readdir(0)
+		assert.Nil(err)
+		assert.True(info != nil)
+		// we don't want to count "migrations", so we're len - 1
+		assert.Equal(len(postgresMigrations)-1, len(info))
+	})
+}