Move ozap plugin under logging package

Add a unit test
Add godoc comments
Add READMEs

Signed-off-by: Alexander Mckenzie-Kelly <alexmk@uk.ibm.com>
open-policy-agent#6499

plugins/logging/README.md → logging/plugins/README.md

@@ -1,4 +1,4 @@
-Logging
+Plug-ins
 ===
 
 This directory contains plug-in support for external logging libraries

logging/plugins/ozap/README.md

@@ -0,0 +1,11 @@
+ozap
+===
+
+ozap is a logging plug-in to wrap [zap](https://github.com/uber-go/zap)
+as a [`logging.Logger`](https://pkg.go.dev/github.com/open-policy-agent/opa/logging#Logger).
+
+```golang
+opa, err := sdk.New(context.Background(), sdk.Options{
+	Logger: ozap.Wrap(logger, level),
+})
+```

plugins/logging/ozap/go.mod → logging/plugins/ozap/go.mod

@@ -1,4 +1,4 @@
-module github.com/open-policy-agent/opa/plugins/logging/ozap
+module github.com/open-policy-agent/opa/logging/plugins/ozap
 
 go 1.21.5
 

logging/plugins/ozap/zap_test.go

@@ -0,0 +1,56 @@
+package ozap
+
+import (
+	"bytes"
+	"errors"
+	"log"
+	"strings"
+	"testing"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+func TestWrapWithFields(t *testing.T) {
+	tests := []struct {
+		name   string
+		fields map[string]interface{}
+		expect []string
+	}{
+		{
+			name: "Ex1",
+			fields: map[string]interface{}{
+				"bad_error":   errors.New("something went wrong"),
+				"context":     "everywhere",
+				"panic":       true,
+				"problems":    99,
+				"luftballons": int64(99),
+			},
+			expect: []string{
+				`"bad_error":"something went wrong"`,
+				`"context":"everywhere"`,
+				`"panic":true`,
+				`"problems":99`,
+				`"luftballons":99`,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			level := zap.NewAtomicLevelAt(zap.InfoLevel)
+			zaplogger := zap.New(zapcore.NewCore(zapcore.NewJSONEncoder(zap.NewDevelopmentEncoderConfig()), zapcore.AddSync(&buf), zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
+				return lvl >= level.Level()
+			})))
+			Wrap(zaplogger, &level).WithFields(tt.fields).Info("test")
+			out := buf.String()
+			for _, e := range tt.expect {
+				if !strings.Contains(out, e) {
+					t.Fail()
+					log.Printf("Missing %s in %s", e, out)
+				}
+			}
+		})
+	}
+}