test: Allow to conditionally skip type tests in new setup (#13712)

Syntax: `@ts-error-if: condition` where condition can be any JS boolean
expression. It may also use any properties from suite config. During the
tests it will then turn into `// @ts-expect-error` commend if condition
evaluates to truthy value and stay the as is otherwise.

Fix prisma/client-planning#65

packages/client/tests/functional/_example/tests.ts

@@ -50,6 +50,11 @@ testMatrix.setupTestSuite(
       expect(schemaString).toContain('datasource')
       expect(schemaString).toContain('model')
     })
+
+    testIf(suiteConfig.provider !== 'mongodb')('conditional @ts-test-if', async () => {
+      // @ts-test-if: provider !== 'mongodb'
+      await prisma.$queryRaw`SELECT 1;`
+    })
   },
   // Use `optOut` to opt out from testing the default selected providers
   // otherwise the suite will require all providers to be specified.

packages/client/tests/functional/_utils/setupFilesAfterEnv.ts

@@ -5,4 +5,7 @@ process.env.DATABASE_URI_postgresql = process.env.TEST_POSTGRES_URI
 process.env.DATABASE_URI_mysql = process.env.TEST_MYSQL_URI
 process.env.DATABASE_URI_cockroachdb = process.env.TEST_COCKROACH_URI
 
+globalThis.testIf = (condition: boolean) => (condition ? test : test.skip)
+globalThis.describeIf = (condition: boolean) => (condition ? describe : describe.skip)
+
 export {}

packages/client/tests/functional/_utils/setupTestSuiteEnv.ts

@@ -1,6 +1,7 @@
 import crypto from 'crypto'
 import fs from 'fs-extra'
 import path from 'path'
+import { Script } from 'vm'
 
 import { DbDrop } from '../../../../migrate/src/commands/DbDrop'
 import { DbPush } from '../../../../migrate/src/commands/DbPush'
@@ -18,21 +19,47 @@ export async function setupTestSuiteFiles(suiteMeta: TestSuiteMeta, suiteConfig:
 
   // we copy the minimum amount of files needed for the test suite
   await fs.copy(path.join(suiteMeta.testDir, 'prisma'), path.join(suiteFolder, 'prisma'))
-  await copyWithImportsAdjust(
+  await copyPreprocessed(
     path.join(suiteMeta.testDir, suiteMeta.testFileName),
     path.join(suiteFolder, suiteMeta.testFileName),
+    suiteConfig,
   )
-  await copyWithImportsAdjust(path.join(suiteMeta.testDir, '_matrix.ts'), path.join(suiteFolder, '_matrix.ts'))
+  await copyPreprocessed(path.join(suiteMeta.testDir, '_matrix.ts'), path.join(suiteFolder, '_matrix.ts'), suiteConfig)
   await fs.copy(path.join(suiteMeta.testDir, 'package.json'), path.join(suiteFolder, 'package.json')).catch(() => {})
 }
 
-async function copyWithImportsAdjust(from: string, to: string): Promise<void> {
+async function copyPreprocessed(from: string, to: string, suiteConfig: TestSuiteConfig): Promise<void> {
   // we adjust the relative paths to work from the generated folder
   const contents = await fs.readFile(from, 'utf8')
-  const newContents = contents.replace(/'..\//g, "'../../../")
+  const newContents = contents
+    .replace(/'..\//g, "'../../../")
+    .replace(/\/\/\s*@ts-test-if:(.+)/g, (match, condition) => {
+      if (!evaluateMagicComment(condition, suiteConfig)) {
+        return '// @ts-expect-error'
+      }
+      return match
+    })
   await fs.writeFile(to, newContents, 'utf8')
 }
 
+/**
+ * Evaluates the condition from @ts-test-if magic comment as
+ * a JS expression.
+ * All properties from suite config are available as variables
+ * within the expression.
+ *
+ * @param conditionFromComment
+ * @param suiteConfig
+ * @returns
+ */
+function evaluateMagicComment(conditionFromComment: string, suiteConfig: TestSuiteConfig): boolean {
+  const script = new Script(conditionFromComment)
+  const value = script.runInNewContext({
+    ...suiteConfig,
+  })
+  return Boolean(value)
+}
+
 /**
  * Write the generated test suite schema to the test suite folder.
  * @param suiteMeta

packages/client/tests/functional/globals.d.ts

@@ -0,0 +1,2 @@
+declare function testIf(condition: boolean): jest.It
+declare function describeIf(condition: boolean): jest.Describe

packages/client/tests/functional/typescript/tests.ts

@@ -35,9 +35,16 @@ function getAllTestSuiteTypeChecks(fileNames: string[]) {
 }
 
 describe('typescript', () => {
-  const suitePaths = glob.sync('./**/.generated/**/*.ts', {
-    ignore: ['./**/.generated/**/*.d.ts', './**/.generated/**/_schema.ts'],
-  })
+  const suitePaths = glob
+    .sync('./**/.generated/**/*.ts', {
+      ignore: ['./**/.generated/**/*.d.ts', './**/.generated/**/_schema.ts'],
+    })
+    // global.d.ts does not really needs typechecking, but
+    // since no sources import it directly, it has to be included
+    // in the source set in order for global `describeIf` and `testIf` to
+    // be discovered
+    .concat([path.resolve(__dirname, '..', 'globals.d.ts')])
+
   const suiteChecks = getAllTestSuiteTypeChecks(suitePaths)
   const suiteTable = map(suitePaths, (path) => [getTestSuiteDisplayName(path), path])