Improve expression validation for short-circuiting expressions

expressions/src/evaluator.ts

@@ -32,7 +32,7 @@ export class Evaluator implements ExprVisitor<data.ExpressionData> {
     return this.eval(this.n);
   }
 
-  private eval(n: Expr): data.ExpressionData {
+  protected eval(n: Expr): data.ExpressionData {
     return n.accept(this);
   }
 

languageservice/src/expression-validation/evaluator.ts

@@ -0,0 +1,61 @@
+import {Evaluator, ExpressionEvaluationError, data} from "@actions/expressions";
+import {Expr, Logical} from "@actions/expressions/ast";
+import {ExpressionData} from "@actions/expressions/data/expressiondata";
+import {TokenType} from "@actions/expressions/lexer";
+import {falsy, truthy} from "@actions/expressions/result";
+import {AccessError} from "./error-dictionary";
+
+export type ValidationError = {
+  message: string;
+  severity: "error" | "warning";
+};
+
+export class ValidationEvaluator extends Evaluator {
+  public readonly errors: ValidationError[] = [];
+
+  public validate() {
+    super.evaluate();
+  }
+
+  protected override eval(n: Expr): ExpressionData {
+    try {
+      return super.eval(n);
+    } catch (e) {
+      // Record error
+      if (e instanceof AccessError) {
+        this.errors.push({
+          message: `Context access might be invalid: ${e.keyName}`,
+          severity: "warning"
+        });
+      } else if (e instanceof ExpressionEvaluationError) {
+        this.errors.push({
+          message: `Expression might be invalid: ${e.message}`,
+          severity: "error"
+        });
+      }
+    }
+
+    // Return null but continue with the validation
+    return new data.Null();
+  }
+
+  override visitLogical(logical: Logical): ExpressionData {
+    let result: data.ExpressionData | undefined;
+
+    for (const arg of logical.args) {
+      const r = this.eval(arg);
+
+      // Simulate short-circuit behavior but continue to evalute all arguments for validation purposes
+      if (
+        !result &&
+        ((logical.operator.type === TokenType.AND && falsy(r)) || (logical.operator.type === TokenType.OR && truthy(r)))
+      ) {
+        result = r;
+      }
+    }
+
+    // result is always assigned before we return here
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    return result!;
+  }
+}

languageservice/src/validate.expressions.test.ts

@@ -46,6 +46,52 @@ jobs:
     ]);
   });
 
+  it("access invalid context field in short-circuited expression", async () => {
+    const result = await validate(
+      createDocument(
+        "wf.yaml",
+        `on: push
+run-name: name-\${{ github.does-not-exist || github.does-not-exist2 }}
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo`
+      )
+    );
+
+    expect(result).toEqual([
+      {
+        message: "Context access might be invalid: does-not-exist",
+        range: {
+          end: {
+            character: 69,
+            line: 1
+          },
+          start: {
+            character: 15,
+            line: 1
+          }
+        },
+        severity: DiagnosticSeverity.Warning
+      },
+      {
+        message: "Context access might be invalid: does-not-exist2",
+        range: {
+          end: {
+            character: 69,
+            line: 1
+          },
+          start: {
+            character: 15,
+            line: 1
+          }
+        },
+        severity: DiagnosticSeverity.Warning
+      }
+    ]);
+  });
+
   it("partial skip access invalid context on incomplete", async () => {
     const contextProviderConfig: ContextProviderConfig = {
       getContext: (context: string) => {

languageservice/src/validate.ts

@@ -1,6 +1,6 @@
-import {Evaluator, ExpressionEvaluationError, Lexer, Parser} from "@actions/expressions";
+import {Lexer, Parser} from "@actions/expressions";
 import {Expr} from "@actions/expressions/ast";
-import {isBasicExpression, isString, ParseWorkflowResult, WorkflowTemplate} from "@actions/workflow-parser";
+import {ParseWorkflowResult, WorkflowTemplate, isBasicExpression, isString} from "@actions/workflow-parser";
 import {ErrorPolicy} from "@actions/workflow-parser/model/convert";
 import {splitAllowedContext} from "@actions/workflow-parser/templates/allowed-context";
 import {BasicExpressionToken} from "@actions/workflow-parser/templates/tokens/basic-expression-token";
@@ -13,9 +13,10 @@ import {TextDocument} from "vscode-languageserver-textdocument";
 import {Diagnostic, DiagnosticSeverity, URI} from "vscode-languageserver-types";
 import {ActionMetadata, ActionReference} from "./action";
 import {ContextProviderConfig} from "./context-providers/config";
-import {getContext, Mode} from "./context-providers/default";
-import {getWorkflowContext, WorkflowContext} from "./context/workflow-context";
-import {AccessError, wrapDictionary} from "./expression-validation/error-dictionary";
+import {Mode, getContext} from "./context-providers/default";
+import {WorkflowContext, getWorkflowContext} from "./context/workflow-context";
+import {wrapDictionary} from "./expression-validation/error-dictionary";
+import {ValidationEvaluator} from "./expression-validation/evaluator";
 import {validatorFunctions} from "./expression-validation/functions";
 import {error} from "./log";
 import {findToken} from "./utils/find-token";
@@ -202,28 +203,17 @@ async function validateExpression(
       continue;
     }
 
-    try {
-      const context = await getContext(namedContexts, contextProviderConfig, workflowContext, Mode.Validation);
+    const context = await getContext(namedContexts, contextProviderConfig, workflowContext, Mode.Validation);
 
-      const e = new Evaluator(expr, wrapDictionary(context), validatorFunctions);
-      e.evaluate();
+    const e = new ValidationEvaluator(expr, wrapDictionary(context), validatorFunctions);
+    e.validate();
 
-      // Any invalid context access would've thrown an error via the `ErrorDictionary`, for now we don't have to check the actual
-      // result of the evaluation.
-    } catch (e) {
-      if (e instanceof AccessError) {
-        diagnostics.push({
-          message: `Context access might be invalid: ${e.keyName}`,
-          severity: DiagnosticSeverity.Warning,
-          range: mapRange(expression.range)
-        });
-      } else if (e instanceof ExpressionEvaluationError) {
-        diagnostics.push({
-          message: `Expression might be invalid: ${e.message}`,
-          severity: DiagnosticSeverity.Error,
-          range: mapRange(expression.range)
-        });
-      }
-    }
+    diagnostics.push(
+      ...e.errors.map(e => ({
+        message: e.message,
+        range: mapRange(expression.range),
+        severity: e.severity === "error" ? DiagnosticSeverity.Error : DiagnosticSeverity.Warning
+      }))
+    );
   }
 }