feat: implement lseq for golang

conformance-tests/runners/golang/main_test.go

@@ -0,0 +1,124 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+
+	"peoplesgrocers.com/code/oss/lseq/golang"
+)
+
+type Operation struct {
+	Before   *int   `json:"before,omitempty"`
+	After    *int   `json:"after,omitempty"`
+	Expected string `json:"expected"`
+}
+
+type Scenario struct {
+	Name        string      `json:"name"`
+	Description string      `json:"description"`
+	Seed        int         `json:"seed"`
+	Init        []string    `json:"init"`
+	RNG         []float64   `json:"rng"`
+	Operations  []Operation `json:"operations"`
+}
+
+func createMockRandom(values []float64) func() float64 {
+	index := 0
+	return func() float64 {
+		if index >= len(values) {
+			panic("ran out of random values")
+		}
+		v := values[index]
+		index++
+		return v
+	}
+}
+
+func TestConformance(t *testing.T) {
+	testDataDir := "../../genfiles"
+	entries, err := os.ReadDir(testDataDir)
+	if err != nil {
+		t.Fatalf("Failed to read test data directory: %v", err)
+	}
+
+	var files []string
+	for _, entry := range entries {
+		if strings.HasSuffix(entry.Name(), ".scenario.json") {
+			files = append(files, entry.Name())
+		}
+	}
+	sort.Strings(files)
+
+	for _, file := range files {
+		filePath := filepath.Join(testDataDir, file)
+		data, err := os.ReadFile(filePath)
+		if err != nil {
+			t.Fatalf("Failed to read %s: %v", file, err)
+		}
+
+		var scenario Scenario
+		if err := json.Unmarshal(data, &scenario); err != nil {
+			t.Fatalf("Failed to parse %s: %v", file, err)
+		}
+
+		t.Run(scenario.Name, func(t *testing.T) {
+			mockRandom := createMockRandom(scenario.RNG)
+			l := lseq.NewLSEQ(mockRandom)
+			state := make([]string, len(scenario.Init))
+			copy(state, scenario.Init)
+
+			for i, op := range scenario.Operations {
+				var beforeKey, afterKey *string
+				var insertIdx int
+
+				if op.Before != nil {
+					// Insert before index X
+					idx := *op.Before
+					if idx < 0 {
+						idx = len(state) + idx
+					}
+					if idx > 0 {
+						beforeKey = &state[idx-1]
+					}
+					if idx < len(state) {
+						afterKey = &state[idx]
+					}
+					insertIdx = idx
+				} else if op.After != nil {
+					// Insert after index X
+					idx := *op.After
+					if idx < 0 {
+						idx = len(state) + idx
+					}
+					if idx >= 0 && idx < len(state) {
+						beforeKey = &state[idx]
+					}
+					if idx+1 < len(state) {
+						afterKey = &state[idx+1]
+					}
+					insertIdx = idx + 1
+				} else {
+					// Neither specified - insert at end
+					if len(state) > 0 {
+						beforeKey = &state[len(state)-1]
+					}
+					insertIdx = len(state)
+				}
+
+				result := l.Alloc(beforeKey, afterKey)
+
+				if result != op.Expected {
+					t.Errorf("op %d: alloc(%v, %v) = %q, want %q",
+						i, beforeKey, afterKey, result, op.Expected)
+				}
+
+				// Insert result into state
+				state = append(state[:insertIdx], append([]string{result}, state[insertIdx:]...)...)
+			}
+		})
+	}
+}