feat: move prune logic in separate file

src/lib/monitor.ts

@@ -12,7 +12,8 @@ import { SingleDepRootResult, DepTree, MonitorMeta, MonitorResult } from './type
 import * as projectMetadata from './project-metadata';
 import * as path from 'path';
 import {MonitorError, ConnectionTimeoutError} from './errors';
-import { SupportedPackageManagers, GRAPH_SUPPORTED_PACKAGE_MANAGERS } from './package-managers';
+import { countPathsToGraphRoot, pruneGraph } from './prune';
+import { GRAPH_SUPPORTED_PACKAGE_MANAGERS } from './package-managers';
 
 const debug = Debug('snyk');
 
@@ -332,44 +333,6 @@ export async function monitorGraph(
   });
 }
 
-export function countPathsToGraphRoot(graph: depGraphLib.DepGraph): number {
-  return graph
-    .getPkgs()
-    .map((pkg) => graph.countPathsToRoot(pkg))
-    .reduce((acc, pathsToRoot) => acc + pathsToRoot, 0);
-}
-
-export async function pruneGraph(
-    depGraph: depGraphLib.DepGraph,
-    packageManager: SupportedPackageManagers,
-  ): Promise<depGraphLib.DepGraph> {
-    try {
-    const threshold = config.PRUNE_DEPS_THRESHOLD; // Arbitrary threshold for maximum number of elements in the tree
-    const prunedTree: DepTree = (await depGraphLib.legacy.graphToDepTree(
-      depGraph,
-      packageManager,
-      { deduplicateWithinTopLevelDeps: true },
-    )) as DepTree;
-
-    const prunedGraph = await depGraphLib.legacy.depTreeToGraph(
-      prunedTree,
-      packageManager,
-    );
-    const count = countPathsToGraphRoot(prunedGraph);
-    debug('prunedPathsCount: ' +  count);
-
-    if (count < threshold) {
-      return prunedGraph;
-    }
-    debug('Too many vulnerable paths to monitor the project');
-    // TODO: create a custom error for this
-    throw new Error('Too many vulnerable paths to monitor the project');
-  } catch (e) {
-    debug('Failed to prune the graph, returning original:' + e);
-    return depGraph;
-  }
-}
-
 function pluckPolicies(pkg) {
   if (!pkg) {
     return null;

src/lib/prune.ts

@@ -0,0 +1,43 @@
+import * as _debug from 'debug';
+import { DepGraph, legacy } from '@snyk/dep-graph';
+
+import { DepTree } from './types';
+import * as config from './config';
+import { SupportedPackageManagers } from './package-managers';
+
+const debug = _debug('snyk:prune');
+
+const {depTreeToGraph, graphToDepTree} = legacy;
+
+export function countPathsToGraphRoot(graph: DepGraph): number {
+  return graph.getPkgs().reduce((acc, pkg) => acc + graph.countPathsToRoot(pkg), 0);
+}
+
+export async function pruneGraph(
+  depGraph: DepGraph,
+  packageManager: SupportedPackageManagers,
+): Promise<DepGraph> {
+  try {
+    // Arbitrary threshold for maximum number of elements in the tree
+    const threshold = config.PRUNE_DEPS_THRESHOLD;
+    const prunedTree = (await graphToDepTree(
+      depGraph,
+      packageManager,
+      { deduplicateWithinTopLevelDeps: true },
+    )) as DepTree;
+
+    const prunedGraph = await depTreeToGraph(prunedTree, packageManager);
+    const count = countPathsToGraphRoot(prunedGraph);
+    debug('prunedPathsCount: ' +  count);
+
+    if (count < threshold) {
+      return prunedGraph;
+    }
+
+    debug('Too many vulnerable paths to process the project');
+    throw new Error('Too many vulnerable paths to process the project');
+  } catch (e) {
+    debug('Failed to prune the graph, returning original: ' + e);
+    return depGraph;
+  }
+}

src/lib/snyk-test/run-test.ts

@@ -25,7 +25,7 @@ import {
 } from '../errors';
 import { maybePrintDeps } from '../print-deps';
 import { SupportedPackageManagers } from '../package-managers';
-import { countPathsToGraphRoot, pruneGraph } from '../monitor';
+import { countPathsToGraphRoot, pruneGraph } from '../prune';
 
 // tslint:disable-next-line:no-var-requires
 const debug = require('debug')('snyk');
@@ -346,7 +346,7 @@ async function assembleLocalPayloads(root, options: Options & TestOptions): Prom
 
           analytics.add('prePrunedPathsCount', prePruneDepCount);
           const postPruneDepCount = countPathsToGraphRoot(depGraph);
-          debug('post prunedPathsCount: ' +  prePruneDepCount);
+          debug('post prunedPathsCount: ' +  postPruneDepCount);
           analytics.add('postPrunedPathsCount', postPruneDepCount);
         }
         body.depGraph = depGraph;