Prometheus: make parsing of Infinity variants case-insensitive (#48660) (#48785)

(cherry picked from commit 6de77283c6)

Co-authored-by: Leon Sorokin <leeoniya@gmail.com>

public/app/plugins/datasource/prometheus/result_transformer.test.ts

@@ -1,6 +1,6 @@
 import { DataFrame, FieldType, DataQueryRequest, DataQueryResponse, MutableDataFrame } from '@grafana/data';
 
-import { transform, transformV2, transformDFToTable } from './result_transformer';
+import { transform, transformV2, transformDFToTable, parseSampleValue } from './result_transformer';
 import { PromQuery } from './types';
 
 jest.mock('@grafana/runtime', () => ({
@@ -33,6 +33,43 @@ const matrixResponse = {
 };
 
 describe('Prometheus Result Transformer', () => {
+  describe('parse variants of "+Inf" and "-Inf" strings', () => {
+    it('+Inf', () => {
+      expect(parseSampleValue('+Inf')).toEqual(Number.POSITIVE_INFINITY);
+    });
+    it('Inf', () => {
+      expect(parseSampleValue('Inf')).toEqual(Number.POSITIVE_INFINITY);
+    });
+    it('inf', () => {
+      expect(parseSampleValue('inf')).toEqual(Number.POSITIVE_INFINITY);
+    });
+    it('+Infinity', () => {
+      expect(parseSampleValue('+Infinity')).toEqual(Number.POSITIVE_INFINITY);
+    });
+    it('+infinity', () => {
+      expect(parseSampleValue('+infinity')).toEqual(Number.POSITIVE_INFINITY);
+    });
+    it('infinity', () => {
+      expect(parseSampleValue('infinity')).toEqual(Number.POSITIVE_INFINITY);
+    });
+
+    it('-Inf', () => {
+      expect(parseSampleValue('-Inf')).toEqual(Number.NEGATIVE_INFINITY);
+    });
+
+    it('-inf', () => {
+      expect(parseSampleValue('-inf')).toEqual(Number.NEGATIVE_INFINITY);
+    });
+
+    it('-Infinity', () => {
+      expect(parseSampleValue('-Infinity')).toEqual(Number.NEGATIVE_INFINITY);
+    });
+
+    it('-infinity', () => {
+      expect(parseSampleValue('-infinity')).toEqual(Number.NEGATIVE_INFINITY);
+    });
+  });
+
   describe('transformV2', () => {
     it('results with time_series format should be enriched with preferredVisualisationType', () => {
       const request = {

public/app/plugins/datasource/prometheus/result_transformer.ts

@@ -38,8 +38,8 @@ import {
   TransformOptions,
 } from './types';
 
-const POSITIVE_INFINITY_SAMPLE_VALUE = '+Inf';
+// handles case-insensitive Inf, +Inf, -Inf (with optional "inity" suffix)
-const NEGATIVE_INFINITY_SAMPLE_VALUE = '-Inf';
+const INFINITY_SAMPLE_REGEX = /^[+-]?inf(?:inity)?$/i;
 
 interface TimeAndValue {
   [TIME_SERIES_TIME_FIELD_NAME]: number;
@@ -611,13 +611,10 @@ function sortSeriesByLabel(s1: DataFrame, s2: DataFrame): number {
   return 0;
 }
 
-function parseSampleValue(value: string): number {
+/** @internal */
-  switch (value) {
+export function parseSampleValue(value: string): number {
-    case POSITIVE_INFINITY_SAMPLE_VALUE:
+  if (INFINITY_SAMPLE_REGEX.test(value)) {
-      return Number.POSITIVE_INFINITY;
+    return value[0] === '-' ? Number.NEGATIVE_INFINITY : Number.POSITIVE_INFINITY;
-    case NEGATIVE_INFINITY_SAMPLE_VALUE:
-      return Number.NEGATIVE_INFINITY;
-    default:
-      return parseFloat(value);
   }
+  return parseFloat(value);
 }