feat: report errors on duplicate actions in resolves (#48)

Fixes #37

src/analysis/properties-analyzer.ts

@@ -26,10 +26,17 @@ class PropertiesAnalyzer extends BoundNodeVisitor {
   }
 
   protected visitResolves(node: BoundResolves): void {
+    const localActions = new Set<string>();
     for (const action of node.actions) {
       if (!this.actions.has(action.value)) {
         this.bag.actionDoesNotExist(action.value, action.syntax.range);
       }
+
+      if (localActions.has(action.value)) {
+        this.bag.duplicateActions(action.value, action.syntax.range);
+      } else {
+        localActions.add(action.value);
+      }
     }
   }
 

src/util/diagnostics.ts

@@ -36,6 +36,7 @@ export enum DiagnosticCode {
   ActionDoesNotExist,
   TooManySecrets,
   DuplicateSecrets,
+  DuplicateActions,
   ReservedEnvironmentVariable,
   UnrecognizedEvent,
 }
@@ -229,6 +230,14 @@ export class DiagnosticBag {
     });
   }
 
+  public duplicateActions(duplicate: string, range: TextRange): void {
+    this.items.push({
+      range,
+      code: DiagnosticCode.DuplicateActions,
+      message: `This 'resolves' property has duplicate '${duplicate}' actions.`,
+    });
+  }
+
   public reservedEnvironmentVariable(range: TextRange): void {
     this.items.push({
       range,

test/properties-analysis.spec.ts

@@ -176,6 +176,30 @@ ERROR: Environment variables starting with 'GITHUB_' are reserved.
   6 |     GITHUBNOUNDERSCORE = \\"2\\"
   7 |     SOMETHING_ELSE = \\"3\\"
 "
+`);
+  });
+
+  it("reports errors on duplicate resolve actions", () => {
+    expectDiagnostics(`
+action "b" {
+  uses = "./ci"
+}
+workflow "c" {
+    on = "fork"
+    resolves = [
+      "b",
+      "b"
+    ]
+}`).toMatchInlineSnapshot(`
+"
+ERROR: This 'resolves' property has duplicate 'b' actions.
+  7 |     resolves = [
+  8 |       \\"b\\",
+  9 |       \\"b\\"
+    |       ^^^
+ 10 |     ]
+ 11 | }
+"
 `);
   });
 });