feat!: validate Avro schemas included in AsyncAPI docs (#96)

This commit adds validation to the avro-schema-parser so that
invalid Avro schemas will be rejected.

I had to fix a few invalid Avro schemas in the tests (which were
using the type 'uuid' which isn't in the Avro spec) so this should
potentially be considered a major breaking change to the parser.

Closes: #37

Signed-off-by: Dale Lane <dale.lane@uk.ibm.com>

README.md

@@ -130,6 +130,38 @@ await parser.parse(asyncapiWithAvro)
 
 ## Features
 
+### Validation of Avro schemas
+
+Avro schemas included in parsed AsyncAPI documents are validated using [avsc](https://www.npmjs.com/package/avsc). Invalid Avro schemas will cause the `parse` function to reject the promise, with an error that explains the problem.
+
+```js
+const assert = require('assert');
+const parser = require('@asyncapi/parser');
+const avroSchemaParser = require('./index');
+
+parser.registerSchemaParser(avroSchemaParser);
+
+const asyncapiWithInvalidAvro = `
+asyncapi: 2.0.0
+info:
+  title: Example with Avro
+  version: 0.1.0
+channels:
+  example:
+    publish:
+      message:
+        schemaFormat: 'application/vnd.apache.avro;version=1.9.0'
+        payload:
+          type: notAValidAvroType
+`;
+
+parser.parse(asyncapiWithInvalidAvro)
+  .catch(err => {
+    assert.strictEqual(err.message,
+      'unknown type: "notAValidAvroType"');
+  });
+```
+
 ### Support of required attributes
 
 Required fields are fields with no default value and without the `"null"` union element.

package.json

@@ -62,5 +62,8 @@
       "@semantic-release/npm",
       "@semantic-release/github"
     ]
+  },
+  "dependencies": {
+    "avsc": "^5.7.3"
   }
 }

tests/asyncapi-avro-broken.yaml

@@ -0,0 +1,11 @@
+asyncapi: 2.0.0
+info:
+  title: My Broken API
+  version: '1.0.0'
+channels:
+  mychannel:
+    publish:
+      message:
+        schemaFormat: application/vnd.apache.avro;version=1.9.0
+        payload:
+          $ref: 'schemas/Person-broken.avsc'

tests/asyncapi-avro-invalid.yaml

@@ -0,0 +1,11 @@
+asyncapi: 2.0.0
+info:
+  title: My Invalid API
+  version: '1.0.0'
+channels:
+  mychannel:
+    publish:
+      message:
+        schemaFormat: application/vnd.apache.avro;version=1.9.0
+        payload:
+          $ref: 'schemas/Invalid.avsc'

tests/schemas/Invalid.avsc

@@ -0,0 +1,3 @@
+{
+  "isThisAnAvroSchema": "no"
+}

tests/schemas/Person-1.9.0-namespace.avsc

@@ -17,6 +17,6 @@
         "fields": [{"name": "zipcode", "type": "int", "example": 53003}]
       }
     },
-    {"name": "someid", "type": "uuid"}
+    {"name": "someid", "type": "string", "logicalType": "uuid"}
   ]
 }

tests/schemas/Person-1.9.0.avsc

@@ -16,6 +16,6 @@
         "fields": [{"name": "zipcode", "type": "int", "example": 53003}]
       }
     },
-    {"name": "someid", "type": "uuid"}
+    {"name": "someid", "type": "string", "logicalType": "uuid"}
   ]
 }

tests/schemas/Person-broken.avsc

@@ -0,0 +1,21 @@
+{
+  "name": "Person",
+  "type": "record",
+  "fields": [
+    {"name": "name", "type": "string", "example": "Donkey"},
+    {"name": "age", "type": ["null", "int"], "default": null, "example": "123"},
+    {
+      "name": "favoriteProgrammingLanguage",
+      "type": {"name": "ProgrammingLanguage", "type": "enum", "symbols": ["JS", "Java", "Go", "Rust", "C"], "default": "JS"}
+    },
+    {
+      "name": "address",
+      "type": {
+        "name": "Address",
+        "type": "record",
+        "fields": [{"name": "zipcode", "type": "notAValidAvroType", "example": "53003"}]
+      }
+    },
+    {"name": "someid", "type": "string", "logicalType": "uuid"}
+  ]
+}

tests/to-json-schema.test.js

@@ -47,11 +47,6 @@ describe('avroToJsonSchema()', function () {
     expect(result).toEqual({type: 'string'});
   });
 
-  it('transforms uuid values', async function () {
-    const result = await avroToJsonSchema({type: 'uuid'});
-    expect(result).toEqual({type: 'string'});
-  });
-
   it('transforms fixed values', async function () {
     const result = await avroToJsonSchema({type: 'fixed', size: 5});
     expect(result).toEqual({type: 'string', pattern: BYTES_PATTERN, minLength: 5, maxLength: 5});

to-json-schema.js

@@ -1,3 +1,5 @@
+const avsc = require('avsc');
+
 const BYTES_PATTERN = '^[\u0000-\u00ff]*$';
 const INT_MIN = Math.pow(-2, 31);
 const INT_MAX = Math.pow(2, 31) - 1;
@@ -126,10 +128,20 @@ const additionalAttributesMapping = (typeInput, avroDefinition, jsonSchemaInput)
   }
 };
 
+function validateAvroSchema(avroDefinition) {
+  // don't need to use the output from parsing the
+  //  avro definition - we're just using this as a
+  //  validator as this will throw an exception if
+  //  there are any problems with the definition
+  avsc.Type.forSchema(avroDefinition);
+}
+
 async function convertAvroToJsonSchema(avroDefinition, isTopLevel) {
   const jsonSchema = {};
   const isUnion = Array.isArray(avroDefinition);
 
+  validateAvroSchema(avroDefinition);
+
   if (isUnion) {
     jsonSchema.oneOf = [];
     let nullDef = null;