Expression evaluator fixes (#1009)

* refactor: remove debug error output

Errors should always be logged with an error level and not debug level.
Since the error is returned here, it will be logged later as an error.
Presumably this was a leftover from debugging the executor chain in:
PR: #971

* refactor: debug log wich expression is going to be evaluated

* fix: handle nil in EvalBool

We've seen this issue when the env map is not set-up properly,
i.e. when the env map is nil, EvalBool might return nil, which should
be handled as a falsy value.

* fix: fail on error in if expression and return the evaluation error

Stop running the workflow in case an expression cannot be evaluated.

Fixes: #1008

* fix: remove quotes from inside expression syntax in test

It looks like having an expression inside double quotes inside the
expression syntax is not valid: https://github.com/ZauberNerd/act-test/actions/runs/1881986429
The workflow is not valid. .github/workflows/test.yml (Line: 10, Col: 13): Unexpected symbol: '"endsWith'. Located at position 1 within expression: "endsWith('Hello world', 'ld')"

* refactor: export IsTruthy function from exprparser package

* refactor: use IsTruthy function in EvalBool

* refactor: move debug log for expression rewrite to rewrite function

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/common/executor.go

@@ -136,7 +136,6 @@ func (e Executor) Then(then Executor) Executor {
 			case Warning:
 				log.Warning(err.Error())
 			default:
-				log.Debugf("%+v", err)
 				return err
 			}
 		}

pkg/exprparser/interpreter.go

@@ -274,7 +274,7 @@ func (impl *interperterImpl) evaluateNot(notNode *actionlint.NotOpNode) (interfa
 		return nil, err
 	}
 
-	return !impl.isTruthy(reflect.ValueOf(operand)), nil
+	return !IsTruthy(operand), nil
 }
 
 func (impl *interperterImpl) evaluateCompare(compareNode *actionlint.CompareOpNode) (interface{}, error) {
@@ -434,7 +434,8 @@ func (impl *interperterImpl) compareNumber(left float64, right float64, kind act
 	}
 }
 
-func (impl *interperterImpl) isTruthy(value reflect.Value) bool {
+func IsTruthy(input interface{}) bool {
+	value := reflect.ValueOf(input)
 	switch value.Kind() {
 	case reflect.Bool:
 		return value.Bool()
@@ -452,10 +453,7 @@ func (impl *interperterImpl) isTruthy(value reflect.Value) bool {
 
 		return value.Float() != 0
 
-	case reflect.Map:
+	case reflect.Map, reflect.Slice:
-		return true
-
-	case reflect.Slice:
 		return true
 
 	default:
@@ -503,14 +501,14 @@ func (impl *interperterImpl) evaluateLogicalCompare(compareNode *actionlint.Logi
 
 	switch compareNode.Kind {
 	case actionlint.LogicalOpNodeKindAnd:
-		if impl.isTruthy(leftValue) {
+		if IsTruthy(left) {
 			return impl.getSafeValue(rightValue), nil
 		}
 
 		return impl.getSafeValue(leftValue), nil
 
 	case actionlint.LogicalOpNodeKindOr:
-		if impl.isTruthy(leftValue) {
+		if IsTruthy(left) {
 			return impl.getSafeValue(leftValue), nil
 		}
 

pkg/runner/expression.go

@@ -2,7 +2,6 @@ package runner
 
 import (
 	"fmt"
-	"math"
 	"regexp"
 	"strings"
 
@@ -128,7 +127,9 @@ type expressionEvaluator struct {
 }
 
 func (ee expressionEvaluator) evaluate(in string, isIfExpression bool) (interface{}, error) {
+	log.Debugf("evaluating expression '%s'", in)
 	evaluated, err := ee.interpreter.Evaluate(in, isIfExpression)
+	log.Debugf("expression '%s' evaluated to '%t'", in, evaluated)
 	return evaluated, err
 }
 
@@ -141,9 +142,6 @@ func (ee expressionEvaluator) evaluateScalarYamlNode(node *yaml.Node) error {
 		return nil
 	}
 	expr, _ := rewriteSubExpression(in, false)
-	if in != expr {
-		log.Debugf("expression '%s' rewritten to '%s'", in, expr)
-	}
 	res, err := ee.evaluate(expr, false)
 	if err != nil {
 		return err
@@ -214,18 +212,12 @@ func (ee expressionEvaluator) Interpolate(in string) string {
 	}
 
 	expr, _ := rewriteSubExpression(in, true)
-	if in != expr {
-		log.Debugf("expression '%s' rewritten to '%s'", in, expr)
-	}
-
 	evaluated, err := ee.evaluate(expr, false)
 	if err != nil {
 		log.Errorf("Unable to interpolate expression '%s': %s", expr, err)
 		return ""
 	}
 
-	log.Debugf("expression '%s' evaluated to '%s'", expr, evaluated)
-
 	value, ok := evaluated.(string)
 	if !ok {
 		panic(fmt.Sprintf("Expression %s did not evaluate to a string", expr))
@@ -237,37 +229,13 @@ func (ee expressionEvaluator) Interpolate(in string) string {
 // EvalBool evaluates an expression against given evaluator
 func EvalBool(evaluator ExpressionEvaluator, expr string) (bool, error) {
 	nextExpr, _ := rewriteSubExpression(expr, false)
-	if expr != nextExpr {
-		log.Debugf("expression '%s' rewritten to '%s'", expr, nextExpr)
-	}
 
 	evaluated, err := evaluator.evaluate(nextExpr, true)
 	if err != nil {
 		return false, err
 	}
 
-	var result bool
+	return exprparser.IsTruthy(evaluated), nil
-
-	switch t := evaluated.(type) {
-	case bool:
-		result = t
-	case string:
-		result = t != ""
-	case int:
-		result = t != 0
-	case float64:
-		if math.IsNaN(t) {
-			result = false
-		} else {
-			result = t != 0
-		}
-	default:
-		return false, fmt.Errorf("Unable to map return type to boolean for '%s'", expr)
-	}
-
-	log.Debugf("expression '%s' evaluated to '%t'", nextExpr, result)
-
-	return result, nil
 }
 
 func escapeFormatString(in string) string {
@@ -334,5 +302,9 @@ func rewriteSubExpression(in string, forceFormat bool) (string, error) {
 		return in, nil
 	}
 
-	return fmt.Sprintf("format('%s', %s)", strings.ReplaceAll(formatOut, "'", "''"), strings.Join(results, ", ")), nil
+	out := fmt.Sprintf("format('%s', %s)", strings.ReplaceAll(formatOut, "'", "''"), strings.Join(results, ", "))
+	if in != out {
+		log.Debugf("expression '%s' rewritten to '%s'", in, out)
+	}
+	return out, nil
 }

pkg/runner/run_context.go

@@ -275,7 +275,18 @@ func (rc *RunContext) steps() []*model.Step {
 
 // Executor returns a pipeline executor for all the steps in the job
 func (rc *RunContext) Executor() common.Executor {
-	return newJobExecutor(rc).If(rc.isEnabled)
+	return func(ctx context.Context) error {
+		isEnabled, err := rc.isEnabled(ctx)
+		if err != nil {
+			return err
+		}
+
+		if isEnabled {
+			return newJobExecutor(rc)(ctx)
+		}
+
+		return nil
+	}
 }
 
 // Executor returns a pipeline executor for all the steps in the job
@@ -405,17 +416,16 @@ func (rc *RunContext) hostname() string {
 	return *hostname
 }
 
-func (rc *RunContext) isEnabled(ctx context.Context) bool {
+func (rc *RunContext) isEnabled(ctx context.Context) (bool, error) {
 	job := rc.Run.Job()
 	l := common.Logger(ctx)
 	runJob, err := EvalBool(rc.ExprEval, job.If.Value)
 	if err != nil {
-		common.Logger(ctx).Errorf("  \u274C  Error in if: expression - %s", job.Name)
+		return false, fmt.Errorf("  \u274C  Error in if-expression: \"if: %s\" (%s)", job.If.Value, err)
-		return false
 	}
 	if !runJob {
 		l.Debugf("Skipping job '%s' due to '%s'", job.Name, job.If.Value)
-		return false
+		return false, nil
 	}
 
 	img := rc.platformImage()
@@ -428,9 +438,9 @@ func (rc *RunContext) isEnabled(ctx context.Context) bool {
 			platformName := rc.ExprEval.Interpolate(runnerLabel)
 			l.Infof("\U0001F6A7  Skipping unsupported platform -- Try running with `-P %+v=...`", platformName)
 		}
-		return false
+		return false, nil
 	}
-	return true
+	return true, nil
 }
 
 func mergeMaps(maps ...map[string]string) map[string]string {

pkg/runner/step_context.go

@@ -171,13 +171,7 @@ func (sc *StepContext) interpolateEnv(exprEval ExpressionEvaluator) {
 func (sc *StepContext) isEnabled(ctx context.Context) (bool, error) {
 	runStep, err := EvalBool(sc.NewExpressionEvaluator(), sc.Step.If.Value)
 	if err != nil {
-		common.Logger(ctx).Errorf("  \u274C  Error in if: expression - %s", sc.Step)
+		return false, fmt.Errorf("  \u274C  Error in if-expression: \"if: %s\" (%s)", sc.Step.If.Value, err)
-		exprEval, err := sc.setupEnv(ctx)
-		if err != nil {
-			return false, err
-		}
-		sc.RunContext.ExprEval = exprEval
-		return false, err
 	}
 
 	return runStep, nil

pkg/runner/testdata/issue-597/spelling.yaml

@@ -1,10 +1,10 @@
 name: issue-597
 on: push
-  
+
 
 jobs:
   my_first_job:
-    
+
     runs-on: ubuntu-latest
     steps:
       - name: My first false step
@@ -14,7 +14,7 @@ jobs:
           ref: refs/pull/${{github.event.pull_request.number}}/merge
           fetch-depth: 5
       - name: My first true step
-        if: ${{"endsWith('Hello world', 'ld')"}}
+        if: ${{endsWith('Hello world', 'ld')}}
         uses: actions/hello-world-javascript-action@main
         with:
           who-to-greet: "Renst the Octocat"

pkg/runner/testdata/uses-composite/push.yml

@@ -17,7 +17,7 @@ jobs:
         secret_input: ${{secrets.test_input_optional || 'NO SUCH SECRET'}}
       env:
         secret_input: ${{secrets.test_input_optional || 'NO SUCH SECRET'}}
-    - if: steps.composite.outputs.test_output != "test_output_value"
+    - if: steps.composite.outputs.test_output != 'test_output_value'
       run: |
         echo "steps.composite.outputs.test_output=${{ steps.composite.outputs.test_output }}"
         exit 1
@@ -38,7 +38,7 @@ jobs:
         test_input_optional_with_default_overriden: 'test_input_optional_with_default_overriden'
         test_input_required_with_default_overriden: 'test_input_required_with_default_overriden'
 
-    - if: steps.composite2.outputs.test_output != "test_output_value"
+    - if: steps.composite2.outputs.test_output != 'test_output_value'
       run: |
         echo "steps.composite.outputs.test_output=${{ steps.composite2.outputs.test_output }}"
         exit 1