fix(agent-task/shared): add ParsePullRequestAgentSessionURL

Signed-off-by: Babak K. Shandiz <babakks@github.com>

pkg/cmd/agent-task/shared/capi.go

@@ -1,13 +1,16 @@
 package shared
 
 import (
+	"errors"
 	"regexp"
 
 	"github.com/cli/cli/v2/pkg/cmd/agent-task/capi"
+	prShared "github.com/cli/cli/v2/pkg/cmd/pr/shared"
 	"github.com/cli/cli/v2/pkg/cmdutil"
 )
 
 var uuidRE = regexp.MustCompile(`^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}$`)
+var agentSessionsPathRE = regexp.MustCompile(`^/agent-sessions/([a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12})$`)
 
 func CapiClientFunc(f *cmdutil.Factory) func() (capi.CapiClient, error) {
 	return func() (capi.CapiClient, error) {
@@ -29,3 +32,20 @@ func CapiClientFunc(f *cmdutil.Factory) func() (capi.CapiClient, error) {
 func IsSessionID(s string) bool {
 	return uuidRE.MatchString(s)
 }
+
+// ParsePullRequestAgentSessionURL parses session ID from a pull request's agent
+// session URL, which is of the form:
+//
+//	https://github.com/OWNER/REPO/pull/NUMBER/agent-sessions/SESSION-ID
+func ParsePullRequestAgentSessionURL(u string) (string, error) {
+	_, _, rest, err := prShared.ParseURL(u)
+	if err != nil {
+		return "", err
+	}
+
+	match := agentSessionsPathRE.FindStringSubmatch(rest)
+	if match == nil {
+		return "", errors.New("not a valid agent session URL")
+	}
+	return match[1], nil
+}

pkg/cmd/agent-task/shared/capi_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestIsSession(t *testing.T) {
@@ -18,3 +19,58 @@ func TestIsSession(t *testing.T) {
 	assert.False(t, IsSessionID("000000000000000000000000000000000000"))
 	assert.False(t, IsSessionID("00000000-0000-0000-0000-000000000000-extra"))
 }
+
+func TestParsePullRequestAgentSessionURL(t *testing.T) {
+	tests := []struct {
+		name          string
+		url           string
+		wantSessionID string
+		wantErr       bool
+	}{
+		{
+			name:          "valid",
+			url:           "https://github.com/OWNER/REPO/pull/123/agent-sessions/e2fa49d2-f164-4a56-ab99-498090b8fcdf",
+			wantSessionID: "e2fa49d2-f164-4a56-ab99-498090b8fcdf",
+		},
+		{
+			name:    "invalid session id",
+			url:     "https://github.com/OWNER/REPO/pull/123/agent-sessions/fff",
+			wantErr: true,
+		},
+		{
+			name:    "no session id, trailing slash",
+			url:     "https://github.com/OWNER/REPO/pull/123/agent-sessions/",
+			wantErr: true,
+		},
+		{
+			name:    "no session id",
+			url:     "https://github.com/OWNER/REPO/pull/123/agent-sessions",
+			wantErr: true,
+		},
+		{
+			name:    "invalid pr url",
+			url:     "https://github.com/OWNER/REPO/issues/123",
+			wantErr: true,
+		},
+		{
+			name:    "empty",
+			url:     "",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sessionID, err := ParsePullRequestAgentSessionURL(tt.url)
+
+			if tt.wantErr {
+				require.Error(t, err)
+				assert.Zero(t, sessionID)
+				return
+			}
+
+			require.NoError(t, err)
+			assert.Equal(t, tt.wantSessionID, sessionID)
+		})
+	}
+}