Handle edge cases with machine mapper: called with no names/ids shoul…

…d be an error and a wildcard with no machines in the cluster (somehow)

internal/machine/api/proxy/mapper.go

@@ -48,6 +48,10 @@ func NewCorrosionMapper(store Store) *CorrosionMapper {
 }
 
 func (m *CorrosionMapper) MapMachines(ctx context.Context, namesOrIDs []string) ([]MachineTarget, error) {
+	if len(namesOrIDs) == 0 {
+		return nil, fmt.Errorf("no machines specified")
+	}
+
 	machines, err := m.store.ListMachines(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("list machines: %w", err)
@@ -67,6 +71,9 @@ func (m *CorrosionMapper) MapMachines(ctx context.Context, namesOrIDs []string)
 	}
 
 	if slices.Contains(namesOrIDs, "*") {
+		if len(allTargets) == 0 {
+			return nil, fmt.Errorf("no machines in cluster")
+		}
 		return allTargets, nil
 	}
 

internal/machine/api/proxy/mapper_test.go

@@ -121,6 +121,13 @@ func TestCorrosionMapper_MapMachines(t *testing.T) {
 			wantErr: true,
 			errMsg:  "machine not found: missing",
 		},
+		{
+			name:    "wildcard with no machines",
+			store:   &mockStore{machines: []*pb.MachineInfo{}},
+			input:   []string{"*"},
+			wantErr: true,
+			errMsg:  "no machines in cluster",
+		},
 		{
 			name:    "store error",
 			store:   &mockStore{err: errors.New("store down")},
@@ -136,10 +143,11 @@ func TestCorrosionMapper_MapMachines(t *testing.T) {
 			errMsg:  "invalid management IP for machine bad-ip",
 		},
 		{
-			name:  "empty input returns empty",
-			store: &mockStore{machines: machines},
-			input: []string{},
-			want:  []MachineTarget{},
+			name:    "empty input returns error",
+			store:   &mockStore{machines: machines},
+			input:   []string{},
+			wantErr: true,
+			errMsg:  "no machines specified",
 		},
 	}