Redefine shouldPerformDiffInformedAnalysis()

This commit renames the original shouldPerformDiffInformedAnalysis(),
which returns `PullRequestBranches | undefined`, to
getDiffInformedAnalysisBranches(). It also adds a new
shouldPerformDiffInformedAnalysis() function that returns boolean.

Separating these two functions makes it clear what the intended uses and
return values should be for each.

src/analyze-action.ts

@@ -22,7 +22,7 @@ import { getCodeQL } from "./codeql";
 import { Config, getConfig } from "./config-utils";
 import { uploadDatabases } from "./database-upload";
 import { uploadDependencyCaches } from "./dependency-caching";
-import { shouldPerformDiffInformedAnalysis } from "./diff-informed-analysis-utils";
+import { getDiffInformedAnalysisBranches } from "./diff-informed-analysis-utils";
 import { EnvVar } from "./environment";
 import { Features } from "./feature-flags";
 import { Language } from "./languages";
@@ -270,7 +270,7 @@ async function run() {
       logger,
     );
 
-    const branches = await shouldPerformDiffInformedAnalysis(
+    const branches = await getDiffInformedAnalysisBranches(
       codeql,
       features,
       logger,

src/diff-informed-analysis-utils.ts

@@ -42,12 +42,26 @@ function getPullRequestBranches(): PullRequestBranches | undefined {
 
 /**
  * Check if the action should perform diff-informed analysis.
+ */
+export async function shouldPerformDiffInformedAnalysis(
+  codeql: CodeQL,
+  features: FeatureEnablement,
+  logger: Logger,
+): Promise<boolean> {
+  return (
+    (await getDiffInformedAnalysisBranches(codeql, features, logger)) !==
+    undefined
+  );
+}
+
+/**
+ * Get the branches to use for diff-informed analysis.
  *
  * @returns If the action should perform diff-informed analysis, return
  * the base and head branches that should be used to compute the diff ranges.
  * Otherwise return `undefined`.
  */
-export async function shouldPerformDiffInformedAnalysis(
+export async function getDiffInformedAnalysisBranches(
   codeql: CodeQL,
   features: FeatureEnablement,
   logger: Logger,