fix: implement nil-safe Context methods on typhon.Request

.github/workflows/actions.yaml

@@ -1,11 +1,11 @@
 name: Run Tests
-on: 
+on:
   - pull_request
 jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.17.x, 1.18.x]
+        go-version: [1.19.x, 1.23.x]
         os: [ubuntu-latest]
     runs-on: ${{ matrix.os }}
     steps:

request.go

@@ -4,14 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	legacyproto "github.com/golang/protobuf/proto"
+	"github.com/monzo/terrors"
+	"google.golang.org/protobuf/proto"
 	"io"
 	"io/ioutil"
 	"net/http"
 	"strings"
-
-	legacyproto "github.com/golang/protobuf/proto"
-	"github.com/monzo/terrors"
-	"google.golang.org/protobuf/proto"
+	"time"
 )
 
 // A Request is Typhon's wrapper around http.Request, used by both clients and servers.
@@ -262,3 +262,35 @@ func NewRawRequest(ctx context.Context, method, url string, body io.ReadCloser)
 	// as an io.ReadCloser, the body won't be encoded as JSON
 	return NewRequest(ctx, method, url, body)
 }
+
+// Deadline wraps the embedded context.Context method to return no deadline if the inner context is nil.
+func (r Request) Deadline() (time.Time, bool) {
+	if r.Context == nil {
+		return time.Time{}, false
+	}
+	return r.Context.Deadline()
+}
+
+// Done wraps the embedded context.Context method to return nil if the inner context is nil.
+func (r Request) Done() <-chan struct{} {
+	if r.Context == nil {
+		return nil
+	}
+	return r.Context.Done()
+}
+
+// Err wraps the embedded context.Context method to return nil if the inner context is nil.
+func (r Request) Err() error {
+	if r.Context == nil {
+		return nil
+	}
+	return r.Context.Err()
+}
+
+// Value wraps the embedded context.Context method to return a nil if the inner context is nil.
+func (r Request) Value(key any) any {
+	if r.Context == nil {
+		return nil
+	}
+	return r.Context.Value(key)
+}

request_test.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/monzo/terrors"
 
@@ -245,6 +246,61 @@ func TestRequestMethod(t *testing.T) {
 	assert.Equal(t, http.MethodGet, req.RequestMethod())
 }
 
+func TestRequestContextImplementation(t *testing.T) {
+	// This test asserts that typhon.Request correctly implements the `context.Context`
+	// interface (including not panicking when these methods are called on the empty
+	// request).
+
+	t.Run("Deadline", func(t *testing.T) {
+		t.Run("returns false on an empty Request", func(t *testing.T) {
+			_, ok := Request{}.Deadline()
+			assert.False(t, ok)
+		})
+
+		t.Run("passes through a non-zero deadline", func(t *testing.T) {
+			ctx, cancel := context.WithDeadline(context.Background(), time.Time{})
+			defer cancel()
+			_, ok := Request{Context: ctx}.Deadline()
+			assert.True(t, ok)
+		})
+	})
+
+	t.Run("Done", func(t *testing.T) {
+		t.Run("returns nil on an empty Request", func(t *testing.T) {
+			assert.Nil(t, Request{}.Done())
+		})
+
+		t.Run("passes through a non-zero Done", func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			assert.NotNil(t, Request{Context: ctx}.Done())
+		})
+	})
+
+	t.Run("Err", func(t *testing.T) {
+		t.Run("returns nil on an empty Request", func(t *testing.T) {
+			assert.Nil(t, Request{}.Err())
+		})
+
+		t.Run("passes through a non-zero Err", func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			cancel()
+			assert.NotNil(t, Request{Context: ctx}.Err())
+		})
+	})
+
+	t.Run("Value", func(t *testing.T) {
+		t.Run("returns nil on an empty Request", func(t *testing.T) {
+			assert.Nil(t, Request{}.Value(struct{}{}))
+		})
+
+		t.Run("passes through a non-zero Value", func(t *testing.T) {
+			ctx := context.WithValue(context.Background(), struct{}{}, true)
+			assert.NotNil(t, Request{Context: ctx}.Value(struct{}{}))
+		})
+	})
+}
+
 func jsonStreamMarshal(v interface{}) ([]byte, error) {
 	var buffer bytes.Buffer
 	writer := bufio.NewWriter(&buffer)