feat: add ListRunnerScaleSets on Client

client.go

@@ -314,6 +314,35 @@ func (c *Client) GetRunnerScaleSet(ctx context.Context, runnerGroupID int, runne
 	}
 }
 
+// ListRunnerScaleSets returns every runner scale set in the given runner group.
+func (c *Client) ListRunnerScaleSets(ctx context.Context, runnerGroupID int) ([]RunnerScaleSet, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	path := fmt.Sprintf("/%s?runnerGroupId=%d", scaleSetEndpoint, runnerGroupID)
+	req, err := c.newActionsServiceRequest(ctx, http.MethodGet, path, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create new actions service request: %w", err)
+	}
+
+	resp, err := c.do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to issue the request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, newRequestResponseError(req, resp, fmt.Errorf("unexpected status code: %d", resp.StatusCode))
+	}
+
+	var list runnerScaleSetsResponse
+	if err := json.NewDecoder(resp.Body).Decode(&list); err != nil {
+		return nil, newRequestResponseError(req, resp, fmt.Errorf("failed to decode runner scale set list: %w", err))
+	}
+
+	return list.RunnerScaleSets, nil
+}
+
 // GetRunnerScaleSetByID fetches a runner scale set by its ID.
 func (c *Client) GetRunnerScaleSetByID(ctx context.Context, runnerScaleSetID int) (*RunnerScaleSet, error) {
 	c.mu.Lock()

client_test.go

@@ -1362,3 +1362,39 @@ kBxfaf3g7iFnl3u8+7Z/7Cb4ZqFcw0bRJseKuR9mFvBhcZxSErbMDEYrevefU9aM
 APeCxEyw6hJXgbWKoG7Fw2g2HP3ytCJ4YzH0zNitHjk/1h4BG7z8cEQILCSv5mN2
 etFcaQuTHEZyRhhJ4BU=
 -----END PRIVATE KEY-----`
+
+func TestListRunnerScaleSets(t *testing.T) {
+	ctx := context.Background()
+	auth := actionsAuth{token: "token"}
+
+	expected := runnerScaleSetsResponse{
+		Count: 2,
+		RunnerScaleSets: []RunnerScaleSet{
+			{ID: 1, Name: "alpha", RunnerGroupID: 1},
+			{ID: 2, Name: "beta", RunnerGroupID: 1},
+		},
+	}
+
+	server := newActionsServer(t, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/tenant/123/_apis/runtime/runnerscalesets" {
+			t.Errorf("path = %q", r.URL.Path)
+		}
+		if r.URL.Query().Get("runnerGroupId") != "1" {
+			t.Errorf("runnerGroupId = %q", r.URL.Query().Get("runnerGroupId"))
+		}
+		if r.URL.Query().Get("name") != "" {
+			t.Errorf("expected no name filter, got %q", r.URL.Query().Get("name"))
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(expected)
+	}))
+
+	client, err := newClient(testSystemInfo, server.configURLForOrg("my-org"), auth)
+	require.NoError(t, err)
+
+	got, err := client.ListRunnerScaleSets(ctx, 1)
+	require.NoError(t, err)
+	require.Len(t, got, 2)
+	assert.Equal(t, "alpha", got[0].Name)
+	assert.Equal(t, "beta", got[1].Name)
+}