Add tests for fourth diagnostic (Go files found but not processed)

Author: owen-mc

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/diagnostics.expected

@@ -0,0 +1,15 @@
+{
+  "internal": false,
+  "markdownMessage": "[Specify a custom build command](https://docs.github.com/en/github-ae@latest/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-the-codeql-workflow-for-compiled-languages#adding-build-steps-for-a-compiled-language) that includes one or more `go build` commands to build the `.go` files to be analyzed.",
+  "severity": "error",
+  "source": {
+    "extractorName": "go",
+    "id": "go/autobuilder/go-files-found-but-not-processed",
+    "name": "Go files were found but not processed"
+  },
+  "visibility": {
+    "cliSummaryTable": true,
+    "statusPage": true,
+    "telemetry": true
+  }
+}

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/test.py

@@ -0,0 +1,9 @@
+import sys
+
+from create_database_utils import *
+from diagnostics_test_utils import *
+
+os.environ['LGTM_INDEX_IMPORT_PATH'] = "test"
+run_codeql_database_create([], lang="go", source="work", db=None, runFunction=runUnsuccessfully)
+
+check_diagnostics()

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/work/go.mod

@@ -0,0 +1,3 @@
+go 1.18
+
+module test

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/work/go.sum

@@ -0,0 +1,3 @@
+go 1.18
+
+module test/subdir

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/work/subdir/go.mod

@@ -0,0 +1,4 @@
+package test/subdir
+
+func Test() {
+}

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/work/subdir/go.sum

@@ -0,0 +1,9 @@
+import sys
+
+from create_database_utils import *
+from diagnostics_test_utils import *
+
+os.environ['LGTM_INDEX_IMPORT_PATH'] = "test"
+run_codeql_database_create([], lang="go", source="work", db=None, runFunction=runUnsuccessfully)
+
+check_diagnostics()

go/ql/integration-tests/all-platforms/go/diagnostics/go-files-found-not-processed/work/subdir/test.go

@@ -0,0 +1 @@
+// The "Go files were found but not processed" diagnostic should not be emitted because there are no go files