chore(cdk-integ-tools): move canonicalizeTemplates internal (#18647)

We're about to deprecate `assert-internal` and `cdk-integ-tools` only uses `canonicalizeTemplates`. There is an argument for canonicalizing assets by default in `assertions` as well, but I am putting that on the backlog for now. For now, just copying over the relevant function which will remove the dependency to `assert-internal`.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

tools/@aws-cdk/cdk-integ-tools/bin/cdk-integ-assert.ts

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 // Verify that all integration tests still match their expected output
-import { canonicalizeTemplate } from '@aws-cdk/assert-internal';
 import { diffTemplate, formatDifferences } from '@aws-cdk/cloudformation-diff';
+import { canonicalizeTemplate } from '../lib/canonicalize-assets';
 import { DEFAULT_SYNTH_OPTIONS, IntegrationTests } from '../lib/integ-helpers';
 
 /* eslint-disable no-console */

tools/@aws-cdk/cdk-integ-tools/lib/canonicalize-assets.ts

@@ -0,0 +1,71 @@
+/**
+ * Reduce template to a normal form where asset references have been normalized
+ *
+ * This makes it possible to compare templates if all that's different between
+ * them is the hashes of the asset values.
+ *
+ * Currently only handles parameterized assets, but can (and should)
+ * be adapted to handle convention-mode assets as well when we start using
+ * more of those.
+ */
+export function canonicalizeTemplate(template: any): any {
+  // For the weird case where we have an array of templates...
+  if (Array.isArray(template)) {
+    return template.map(canonicalizeTemplate);
+  }
+
+  // Find assets via parameters
+  const stringSubstitutions = new Array<[RegExp, string]>();
+  const paramRe = /^AssetParameters([a-zA-Z0-9]{64})(S3Bucket|S3VersionKey|ArtifactHash)([a-zA-Z0-9]{8})$/;
+
+  const assetsSeen = new Set<string>();
+  for (const paramName of Object.keys(template?.Parameters || {})) {
+    const m = paramRe.exec(paramName);
+    if (!m) { continue; }
+    if (assetsSeen.has(m[1])) { continue; }
+
+    assetsSeen.add(m[1]);
+    const ix = assetsSeen.size;
+
+    // Full parameter reference
+    stringSubstitutions.push([
+      new RegExp(`AssetParameters${m[1]}(S3Bucket|S3VersionKey|ArtifactHash)([a-zA-Z0-9]{8})`),
+      `Asset${ix}$1`,
+    ]);
+    // Substring asset hash reference
+    stringSubstitutions.push([
+      new RegExp(`${m[1]}`),
+      `Asset${ix}Hash`,
+    ]);
+  }
+
+  // Substitute them out
+  return substitute(template);
+
+  function substitute(what: any): any {
+    if (Array.isArray(what)) {
+      return what.map(substitute);
+    }
+
+    if (typeof what === 'object' && what !== null) {
+      const ret: any = {};
+      for (const [k, v] of Object.entries(what)) {
+        ret[stringSub(k)] = substitute(v);
+      }
+      return ret;
+    }
+
+    if (typeof what === 'string') {
+      return stringSub(what);
+    }
+
+    return what;
+  }
+
+  function stringSub(x: string) {
+    for (const [re, replacement] of stringSubstitutions) {
+      x = x.replace(re, replacement);
+    }
+    return x;
+  }
+}

tools/@aws-cdk/cdk-integ-tools/package.json

@@ -39,7 +39,6 @@
   "dependencies": {
     "@aws-cdk/cloudformation-diff": "0.0.0",
     "@aws-cdk/cx-api": "0.0.0",
-    "@aws-cdk/assert-internal": "0.0.0",
     "aws-cdk": "0.0.0",
     "fs-extra": "^9.1.0",
     "yargs": "^16.2.0"
@@ -52,9 +51,6 @@
   "engines": {
     "node": ">= 10.13.0 <13 || >=13.7.0"
   },
-  "peerDependencies": {
-    "@aws-cdk/assert-internal": "0.0.0"
-  },
   "ubergen": {
     "exclude": true
   }