prometheus: monaco: fix a corner-case with quotes (#41345)

public/app/plugins/datasource/prometheus/components/monaco-query-field/monaco-completion-provider/situation.test.ts

@@ -140,6 +140,10 @@ describe('situation', () => {
       otherLabels: [{ name: 'job', value: 'j1', op: '=' }],
     });
 
+    assertSituation('something{job="j1"^}', null);
+    assertSituation('something{job="j1" ^ }', null);
+    assertSituation('something{job="j1" ^   ,   }', null);
+
     assertSituation('{job=^,host="h1"}', {
       type: 'IN_LABEL_SELECTOR_WITH_LABEL_NAME',
       labelName: 'job',

public/app/plugins/datasource/prometheus/components/monaco-query-field/monaco-completion-provider/situation.ts

@@ -410,12 +410,29 @@ function resolveLabelKeysWithEquals(node: SyntaxNode, text: string, pos: number)
   // for example `something{^}`
 
   // there are some false positives that can end up in this situation, that we want
-  // to eliminate, for example: `something{a~^}`
+  // to eliminate:
-  // basically, if this subtree contains any error-node, we stop
+  // `something{a~^}` (if this subtree contains any error-node, we stop)
   if (subTreeHasError(node)) {
     return null;
   }
 
+  // next false positive:
+  // `something{a="1"^}`
+  const child = walk(node, [['firstChild', 'LabelMatchList']]);
+  if (child !== null) {
+    // means the label-matching part contains at least one label already.
+    //
+    // in this case, we will need to have a `,` character at the end,
+    // to be able to suggest adding the next label.
+    // the area between the end-of-the-child-node and the cursor-pos
+    // must contain a `,` in this case.
+    const textToCheck = text.slice(child.to, pos);
+
+    if (!textToCheck.includes(',')) {
+      return null;
+    }
+  }
+
   const metricNameNode = walk(node, [
     ['parent', 'VectorSelector'],
     ['firstChild', 'MetricIdentifier'],