integration: make debugJSON and execJSON methods

Go 1.27 allows type parameters on methods, so the container no longer has
to be passed as the first argument.

integration/hsic/hsic.go

@@ -1723,31 +1723,31 @@ func (t *HeadscaleInContainer) SendInterrupt() error {
 }
 
 func (t *HeadscaleInContainer) GetAllMapReponses() (map[types.NodeID][]tailcfg.MapResponse, error) {
-	return debugJSON[map[types.NodeID][]tailcfg.MapResponse](t, "mapresponses")
+	return t.debugJSON[map[types.NodeID][]tailcfg.MapResponse]("mapresponses")
 }
 
 // PrimaryRoutes fetches the primary routes from the debug endpoint.
 func (t *HeadscaleInContainer) PrimaryRoutes() (*types.DebugRoutes, error) {
-	return debugJSON[*types.DebugRoutes](t, "routes")
+	return t.debugJSON[*types.DebugRoutes]("routes")
 }
 
 // DebugBatcher fetches the batcher debug information from the debug endpoint.
 func (t *HeadscaleInContainer) DebugBatcher() (*hscontrol.DebugBatcherInfo, error) {
-	return debugJSON[*hscontrol.DebugBatcherInfo](t, "batcher")
+	return t.debugJSON[*hscontrol.DebugBatcherInfo]("batcher")
 }
 
 // DebugNodeStore fetches the [state.NodeStore] data from the debug endpoint.
 func (t *HeadscaleInContainer) DebugNodeStore() (map[types.NodeID]types.Node, error) {
-	return debugJSON[map[types.NodeID]types.Node](t, "nodestore")
+	return t.debugJSON[map[types.NodeID]types.Node]("nodestore")
 }
 
 // DebugFilter fetches the current filter rules from the debug endpoint.
 func (t *HeadscaleInContainer) DebugFilter() ([]tailcfg.FilterRule, error) {
-	return debugJSON[[]tailcfg.FilterRule](t, "filter")
+	return t.debugJSON[[]tailcfg.FilterRule]("filter")
 }
 
 // debugJSON fetches and decodes a JSON-returning debug endpoint by name.
-func debugJSON[T any](t *HeadscaleInContainer, endpoint string) (T, error) {
+func (t *HeadscaleInContainer) debugJSON[T any](endpoint string) (T, error) {
 	var res T
 
 	// Execute curl inside the container to access the debug endpoint locally

integration/tsic/tsic.go

@@ -954,8 +954,7 @@ func (t *TailscaleInContainer) MustIPv6() netip.Addr {
 // fresh T, and returns the value alongside the raw JSON for callers that persist
 // it. stderr is printed when the command fails. execErr and unmarshalErr provide
 // the error context used in test diagnostics.
-func execJSON[T any](
-	t *TailscaleInContainer,
+func (t *TailscaleInContainer) execJSON[T any](
 	command []string,
 	execErr, unmarshalErr string,
 ) (*T, string, error) {
@@ -983,8 +982,7 @@ func (t *TailscaleInContainer) Status(save ...bool) (*ipnstate.Status, error) {
 		"--json",
 	}
 
-	status, raw, err := execJSON[ipnstate.Status](
-		t,
+	status, raw, err := t.execJSON[ipnstate.Status](
 		command,
 		"executing tailscale status command",
 		"unmarshalling tailscale status",
@@ -1040,8 +1038,7 @@ func (t *TailscaleInContainer) Netmap() (*netmap.NetworkMap, error) {
 		"netmap",
 	}
 
-	nm, raw, err := execJSON[netmap.NetworkMap](
-		t,
+	nm, raw, err := t.execJSON[netmap.NetworkMap](
 		command,
 		"executing tailscale debug netmap command",
 		"unmarshalling tailscale netmap",
@@ -1165,8 +1162,7 @@ func (t *TailscaleInContainer) DebugDERPRegion(region string) (*ipnstate.DebugDE
 		region,
 	}
 
-	report, _, err := execJSON[ipnstate.DebugDERPRegionReport](
-		t,
+	report, _, err := t.execJSON[ipnstate.DebugDERPRegionReport](
 		command,
 		"executing tailscale debug derp command",
 		"unmarshalling tailscale derp region report",
@@ -1186,8 +1182,7 @@ func (t *TailscaleInContainer) Netcheck() (*netcheck.Report, error) {
 		"--format=json",
 	}
 
-	nm, _, err := execJSON[netcheck.Report](
-		t,
+	nm, _, err := t.execJSON[netcheck.Report](
 		command,
 		"executing tailscale debug netcheck command",
 		"unmarshalling tailscale netcheck",