lang: funcs: Add runner pure func execution

This adds a function runner that runs pure functions. It will hopefully
be useful for speculative execution of functions for compile time
determination of types.

lang/funcs/core/core_test.go

@@ -0,0 +1,165 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// +build !root
+
+package core
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/purpleidea/mgmt/lang/funcs"
+	"github.com/purpleidea/mgmt/lang/types"
+	"github.com/purpleidea/mgmt/util"
+
+	"github.com/davecgh/go-spew/spew"
+	"github.com/kylelemons/godebug/pretty"
+)
+
+func TestPureFuncExec0(t *testing.T) {
+	type test struct { // an individual test
+		name     string
+		funcname string
+		args     []types.Value
+		fail     bool
+		expect   types.Value
+	}
+	testCases := []test{}
+
+	//{
+	//	testCases = append(testCases, test{
+	//		name: "",
+	//		funcname: "",
+	//		args: []types.Value{
+	//		},
+	//		fail: false,
+	//		expect: nil,
+	//	})
+	//}
+	{
+		testCases = append(testCases, test{
+			name:     "strings.to_lower 0",
+			funcname: "strings.to_lower",
+			args: []types.Value{
+				&types.StrValue{
+					V: "HELLO",
+				},
+			},
+			fail: false,
+			expect: &types.StrValue{
+				V: "hello",
+			},
+		})
+	}
+	{
+		testCases = append(testCases, test{
+			name:     "datetime.now fail",
+			funcname: "datetime.now",
+			args:     nil,
+			fail:     true,
+			expect:   nil,
+		})
+	}
+	// TODO: run unification in PureFuncExec if it makes sense to do so...
+	//{
+	//	testCases = append(testCases, test{
+	//		name:     "len 0",
+	//		funcname: "len",
+	//		args: []types.Value{
+	//			&types.StrValue{
+	//				V: "Hello, world!",
+	//			},
+	//		},
+	//		fail: false,
+	//		expect: &types.IntValue{
+	//			V: 13,
+	//		},
+	//	})
+	//}
+
+	names := []string{}
+	for index, tc := range testCases { // run all the tests
+		if tc.name == "" {
+			t.Errorf("test #%d: not named", index)
+			continue
+		}
+		if util.StrInList(tc.name, names) {
+			t.Errorf("test #%d: duplicate sub test name of: %s", index, tc.name)
+			continue
+		}
+		names = append(names, tc.name)
+
+		//if index != 3 { // hack to run a subset (useful for debugging)
+		//if (index != 20 && index != 21) {
+		//if tc.name != "nil" {
+		//	continue
+		//}
+
+		t.Run(fmt.Sprintf("test #%d (%s)", index, tc.name), func(t *testing.T) {
+			name, funcname, args, fail, expect := tc.name, tc.funcname, tc.args, tc.fail, tc.expect
+
+			t.Logf("\n\ntest #%d (%s) ----------------\n\n", index, name)
+
+			f, err := funcs.Lookup(funcname)
+			if err != nil {
+				t.Errorf("test #%d: func lookup failed with: %+v", index, err)
+				return
+			}
+
+			result, err := funcs.PureFuncExec(f, args)
+
+			if !fail && err != nil {
+				t.Errorf("test #%d: func failed with: %+v", index, err)
+				return
+			}
+			if fail && err == nil {
+				t.Errorf("test #%d: func passed, expected fail", index)
+				return
+			}
+			if !fail && result == nil {
+				t.Errorf("test #%d: func output was nil", index)
+				return
+			}
+
+			if !reflect.DeepEqual(result, expect) {
+				// double check because DeepEqual is different since the func exists
+				diff := pretty.Compare(result, expect)
+				if diff != "" { // bonus
+					t.Errorf("test #%d: result did not match expected", index)
+					// TODO: consider making our own recursive print function
+					t.Logf("test #%d:   actual: \n\n%s\n", index, spew.Sdump(result))
+					t.Logf("test #%d: expected: \n\n%s", index, spew.Sdump(expect))
+
+					// more details, for tricky cases:
+					diffable := &pretty.Config{
+						Diffable:          true,
+						IncludeUnexported: true,
+						//PrintStringers: false,
+						//PrintTextMarshalers: false,
+						//SkipZeroFields: false,
+					}
+					t.Logf("test #%d:   actual: \n\n%s\n", index, diffable.Sprint(result))
+					t.Logf("test #%d: expected: \n\n%s", index, diffable.Sprint(expect))
+					t.Logf("test #%d: diff:\n%s", index, diff)
+					return
+				}
+			}
+		})
+	}
+}