Improve error compatibility, update README

.github/workflows/test.yml

@@ -9,17 +9,14 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        go-version: [ '1.22', '1.23' ]
 
     steps:
     - uses: actions/checkout@v4
 
     - name: Set up Go
       uses: actions/setup-go@v5
       with:
-        go-version: ${{ matrix.go-version }}
+        go-version: '1.25'
 
     - name: Run tests
       run: make test

Makefile

@@ -1,7 +1,7 @@
 .PHONY: test integration lint build clean
 
 test:
-	go test -v -race -cover ./...
+	go test -race -cover ./...
 
 DS9_TEST_PROJECT ?= integration-testing-476513
 DS9_TEST_DATABASE ?= ds9-test

README.md

@@ -1,8 +1,15 @@
 # ds9
 
-Zero-dependency Google Cloud Datastore client for Go. Drop-in replacement for `cloud.google.com/go/datastore` basic operations. In-memory mock implementation. Comprehensive testing.
+<img src="media/logo-small.png" alt="ds9 logo" align="right">
 
-**Why?** The official client has 50+ dependencies. `ds9` uses only Go stdlib—ideal for lightweight services and minimizing supply chain risk.
+[![Go Reference](https://pkg.go.dev/badge/github.com/codeGROOVE-dev/ds9.svg)](https://pkg.go.dev/github.com/codeGROOVE-dev/ds9)
+[![Go Report Card](https://goreportcard.com/badge/github.com/codeGROOVE-dev/ds9)](https://goreportcard.com/report/github.com/codeGROOVE-dev/ds9)
+[![License: Apache 2.0](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
+[![Go Version](https://img.shields.io/github/go-mod/go-version/codeGROOVE-dev/ds9)](go.mod)
+
+Zero-dependency Google Cloud Datastore client for Go. Drop-in replacement for `cloud.google.com/go/datastore` with CRUD, transactions, queries, cursors, and mutations. In-memory mock implementation. Comprehensive testing.
+
+**Why?** The official client has 50+ dependencies. `ds9` has zero—ideal for lightweight services and minimizing supply chain risk.
 
 ## Installation
 
@@ -36,6 +43,7 @@ Just switch the import path from `cloud.google.com/go/datastore` to `github.com/
 - **Cursors**: Start, End, DecodeCursor
 - **Keys**: NameKey, IDKey, IncompleteKey, AllocateIDs, parent keys
 - **Mutations**: NewInsert, NewUpdate, NewUpsert, NewDelete, Mutate
+- **Errors**: ErrNoSuchEntity, ErrInvalidKey, ErrInvalidEntityType, ErrConcurrentTransaction, Done, MultiError
 - **Types**: string, int, int64, int32, bool, float64, time.Time, slices ([]string, []int64, []int, []float64, []bool)
 
 **Unsupported Features**
@@ -46,6 +54,6 @@ These features are unsupported just because we haven't found a use for the featu
 
 ## Testing
 
-* Use `github.com/codeGROOVE-dev/ds9/pkg/mock` package for in-memory testing. It should work even if you choose not to use ds9.
+* Use `datastore.NewMockClient(t)` for in-memory testing. Works even if you're still using the official client.
 * See [TESTING.md](TESTING.md) for integration tests.
 * We aim to maintain 85% test coverage - please don't send PRs without tests.

integration/integration_test.go

@@ -186,8 +186,19 @@ func TestIntegrationBatchOperations(t *testing.T) {
 
 		var retrieved []integrationEntity
 		err = client.GetMulti(ctx, keys, &retrieved)
-		if !errors.Is(err, datastore.ErrNoSuchEntity) {
-			t.Errorf("expected datastore.ErrNoSuchEntity after DeleteMulti, got %v", err)
+		if err == nil {
+			t.Fatal("expected error after DeleteMulti, got nil")
+		}
+
+		var multiErr datastore.MultiError
+		if !errors.As(err, &multiErr) {
+			t.Fatalf("expected MultiError after DeleteMulti, got %T: %v", err, err)
+		}
+
+		for i, e := range multiErr {
+			if !errors.Is(e, datastore.ErrNoSuchEntity) {
+				t.Errorf("expected ErrNoSuchEntity at index %d, got %v", i, e)
+			}
 		}
 	})
 }

pkg/datastore/cursor_coverage_test.go

@@ -115,7 +115,7 @@ func TestCursorWithLimitedResults(t *testing.T) {
 	for {
 		var entity testEntity
 		_, err := it.Next(&entity)
-		if errors.Is(err, datastore.ErrDone) {
+		if errors.Is(err, datastore.Done) {
 			break
 		}
 		if err != nil {

pkg/datastore/entity_coverage_test.go

@@ -212,7 +212,7 @@ func TestIterator_Coverage(t *testing.T) {
 			Time  time.Time
 		}
 		_, err := it.Next(&entity)
-		if errors.Is(err, ErrDone) {
+		if errors.Is(err, Done) {
 			break
 		}
 		if err != nil {

pkg/datastore/errors.go

@@ -1,11 +1,53 @@
 package datastore
 
-import "errors"
+import (
+	"errors"
+	"fmt"
+)
 
 var (
-	// ErrNoSuchEntity is returned when an entity is not found.
+	// ErrInvalidEntityType is returned when functions like Get or Next are
+	// passed a dst or src argument of invalid type.
+	ErrInvalidEntityType = errors.New("datastore: invalid entity type")
+
+	// ErrInvalidKey is returned when an invalid key is presented.
+	ErrInvalidKey = errors.New("datastore: invalid key")
+
+	// ErrNoSuchEntity is returned when no entity was found for a given key.
 	ErrNoSuchEntity = errors.New("datastore: no such entity")
 
-	// ErrDone is returned by Iterator.Next when no more results are available.
-	ErrDone = errors.New("datastore: no more results")
+	// ErrConcurrentTransaction is returned when a transaction is used concurrently.
+	ErrConcurrentTransaction = errors.New("datastore: concurrent transaction")
+
+	// Done is returned by Iterator.Next when no more results are available.
+	// This matches the official cloud.google.com/go/datastore API.
+	//
+	//nolint:revive,errname,staticcheck // Name must match official API (iterator.Done)
+	Done = errors.New("datastore: no more items in iterator")
 )
+
+// MultiError is returned by batch operations when there are errors with
+// particular elements. Errors will be in a one-to-one correspondence with
+// the input elements; successful elements will have a nil entry.
+type MultiError []error
+
+func (m MultiError) Error() string {
+	s, n := "", 0
+	for _, e := range m {
+		if e != nil {
+			if n == 0 {
+				s = e.Error()
+			}
+			n++
+		}
+	}
+	switch n {
+	case 0:
+		return "(0 errors)"
+	case 1:
+		return s
+	case 2:
+		return s + " (and 1 other error)"
+	}
+	return fmt.Sprintf("%s (and %d other errors)", s, n-1)
+}

pkg/datastore/iterator.go

@@ -41,7 +41,7 @@ func (it *Iterator) Next(dst any) (*Key, error) {
 			return nil, it.err
 		}
 		if !it.fetchNext {
-			return nil, ErrDone
+			return nil, Done
 		}
 
 		// Fetch next batch
@@ -51,7 +51,7 @@ func (it *Iterator) Next(dst any) (*Key, error) {
 		}
 
 		if len(it.results) == 0 {
-			return nil, ErrDone
+			return nil, Done
 		}
 	}
 

pkg/datastore/iterator_coverage_test.go

@@ -64,7 +64,7 @@ func TestIteratorMultipleFetches(t *testing.T) {
 			Time  time.Time
 		}
 		_, err := it.Next(&entity)
-		if errors.Is(err, ErrDone) {
+		if errors.Is(err, Done) {
 			break
 		}
 		if err != nil {
@@ -209,7 +209,7 @@ func TestIteratorKeysOnly(t *testing.T) {
 			Data string
 		}
 		key, err := it.Next(&entity)
-		if errors.Is(err, ErrDone) {
+		if errors.Is(err, Done) {
 			break
 		}
 		if err != nil {

pkg/datastore/iterator_test.go

@@ -35,7 +35,7 @@ func TestIterator(t *testing.T) {
 		for {
 			var entity testEntity
 			key, err := it.Next(&entity)
-			if errors.Is(err, datastore.ErrDone) {
+			if errors.Is(err, datastore.Done) {
 				break
 			}
 			if err != nil {
@@ -89,8 +89,8 @@ func TestIterator(t *testing.T) {
 
 		var entity testEntity
 		_, err := it.Next(&entity)
-		if !errors.Is(err, datastore.ErrDone) {
-			t.Errorf("Expected datastore.ErrDone, got %v", err)
+		if !errors.Is(err, datastore.Done) {
+			t.Errorf("Expected datastore.Done, got %v", err)
 		}
 	})
 }