fix: never show one az account's subscriptions under another

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/provider/azure/accounts_test.go

@@ -2,6 +2,7 @@ package azure
 
 import (
 	"context"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"os"
@@ -11,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
 )
 
@@ -67,7 +69,9 @@ func TestAccountLabels(t *testing.T) {
 
 func TestCLICredentialPinsAccount(t *testing.T) {
 	var calls [][]string
-	c := newCLICredential("s-alice-2", "t1")
+	c := newCLICredential("alice@contoso.com", "t1", func() ([]account, error) {
+		return []account{{user: "alice@contoso.com", tenant: "t1", anchor: "s-alice-2"}}, nil
+	})
 	c.run = func(_ context.Context, args ...string) ([]byte, error) {
 		calls = append(calls, args)
 		exp := time.Now().Add(time.Hour).Unix()
@@ -102,7 +106,7 @@ func TestCLICredentialPinsAccount(t *testing.T) {
 
 func TestCLICredentialRenewsAndReportsErrors(t *testing.T) {
 	n := 0
-	c := newCLICredential("", "")
+	c := newCLICredential("", "", nil)
 	c.run = func(context.Context, ...string) ([]byte, error) {
 		n++
 		if n == 2 {
@@ -119,3 +123,69 @@ func TestCLICredentialRenewsAndReportsErrors(t *testing.T) {
 		t.Errorf("err = %v", err)
 	}
 }
+
+// jwt is an unsigned token with claims, as az would print it.
+func jwt(claims string) string {
+	enc := base64.RawURLEncoding.EncodeToString
+	return enc([]byte(`{"alg":"none"}`)) + "." + enc([]byte(claims)) + ".sig"
+}
+
+func TestCLICredentialFollowsAzAndRefusesOtherUsers(t *testing.T) {
+	// az's profile has one entry per subscription: signing in as bob,
+	// who also sees s-shared, moved it from alice to bob.
+	profile := []account{
+		{user: "alice@contoso.com", tenant: "t1", anchor: "s-shared"},
+		{user: "bob@contoso.com", tenant: "t1", anchor: "s-bob"},
+	}
+	var args []string
+	issuedTo := "alice@contoso.com"
+	c := newCLICredential("alice@contoso.com", "t1", func() ([]account, error) { return profile, nil })
+	c.run = func(_ context.Context, a ...string) ([]byte, error) {
+		args = a
+		exp := time.Now().Add(time.Hour).Unix()
+		return []byte(fmt.Sprintf(`{"accessToken": %q, "expires_on": %d}`, jwt(`{"upn":"`+issuedTo+`"}`), exp)), nil
+	}
+	arm := policy.TokenRequestOptions{Scopes: []string{"https://management.azure.com/.default"}}
+	if _, err := c.GetToken(context.Background(), arm); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(strings.Join(args, " "), "--subscription s-shared") {
+		t.Errorf("args %q", args)
+	}
+
+	// Now alice has another subscription, and az would hand out bob's
+	// token for the old one: the new pin is used, and bob's token refused.
+	profile[0].anchor = "s-alice"
+	c.cache = map[string]azcore.AccessToken{}
+	issuedTo = "bob@contoso.com"
+	_, err := c.GetToken(context.Background(), arm)
+	if !strings.Contains(strings.Join(args, " "), "--subscription s-alice") {
+		t.Errorf("args %q", args)
+	}
+	if err == nil || !strings.Contains(err.Error(), "token for bob@contoso.com, not alice@contoso.com") {
+		t.Errorf("err = %v", err)
+	}
+
+	// Alice gone from az entirely: sign in again.
+	profile = profile[1:]
+	if _, err := c.GetToken(context.Background(), arm); err == nil || !strings.Contains(err.Error(), "sign in as alice@contoso.com") {
+		t.Errorf("err = %v", err)
+	}
+}
+
+func TestTokenUser(t *testing.T) {
+	users := []string{"bob@contoso.com"}
+	for claims, want := range map[string]bool{
+		`{"upn":"Bob@Contoso.com"}`:                        true,
+		`{"unique_name":"live.com#bob@contoso.com"}`:       true,
+		`{"upn":"alice@contoso.com"}`:                      false,
+		`{"appid":"00000000-0000-0000-0000-000000000000"}`: false,
+	} {
+		if _, got := tokenUser(jwt(claims), users); got != want {
+			t.Errorf("%s: %v", claims, got)
+		}
+	}
+	if _, got := tokenUser("not-a-jwt", users); got {
+		t.Error("not a JWT")
+	}
+}