[#2] Add a custom vm.Run() function

It executes loaded program and accumulates all seen opcodes
together with the scripthash they belong to.

Signed-off-by: Ekaterina Lebedeva <ekaterina.lebedeva@yadro.com>

covertest/run.go

@@ -0,0 +1,58 @@
+package covertest
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
+	"github.com/nspcc-dev/neo-go/pkg/vm/vmstate"
+)
+
+// InstrHash maps Instruction with its Script Hash.
+type InstrHash struct {
+	Num         int
+	Instruction opcode.Opcode
+	ScriptHash  util.Uint160
+}
+
+// Run starts execution of the loaded program and accumulates all seen opcodes
+// together with the scripthash they belong to.
+func Run(v *vm.VM) ([]InstrHash, error) {
+
+	if !v.Ready() {
+		return nil, errors.New("no program loaded")
+	}
+
+	if v.HasFailed() {
+		// VM already ran something and failed, in general its state is
+		// undefined in this case so we can't run anything.
+		return nil, errors.New("VM has failed")
+	}
+
+	// vmstate.Halt (the default) or vmstate.Break are safe to continue.
+	var ops []InstrHash
+	for {
+		switch {
+		case v.HasFailed():
+			// Should be caught and reported already by the v.Step(),
+			// but we're checking here anyway just in case.
+			return ops, errors.New("VM has failed")
+		case v.HasHalted(), v.AtBreakpoint():
+			// Normal exit from this loop.
+			return ops, nil
+		case v.State() == vmstate.None:
+			nStr, curInstr := v.Context().NextInstr()
+			ops = append(ops, InstrHash{
+				Num:         nStr,
+				Instruction: curInstr,
+				ScriptHash:  v.Context().ScriptHash(),
+			})
+			if err := v.Step(); err != nil {
+				return ops, err
+			}
+		default:
+			return ops, errors.New("unknown state")
+		}
+	}
+}