fix(module): coverage over nothing is not coverage

.gds/bundle.lock.yaml

@@ -5,14 +5,14 @@ bundle:
   version: "0.4.0-dev"
   release_sequence: 0
   channel: "development"
-  source_tree_digest: "sha256:a18f15d00b467f9585fecf7ee3230f00025f69726e17135f14eb99f3036b5827"
-  digest: "sha256:7d370fff3455208269852d3bd0f7e4eff1e61b3eb8e80df9c967245bf464cda5"
+  source_tree_digest: "sha256:66532e92cee2ba8351911491ea4d8267fe853db10ebe36559551cb21aad5f209"
+  digest: "sha256:02032875c4b1e479d953ba4e9b766cf260bc469a81c38856ab6a6c6044b1c147"
 
 projection:
-  input_digest: "sha256:88f5073a543617f2b37990db826b8777ef8c396eb658de403f60e2e480e15f62"
-  output_digest: "sha256:d76ab0b017214dce592c2ae8b23e30b89caabf5a0197be3b25dae6d948cd00aa"
+  input_digest: "sha256:02a7ff040caee7de0f5de1b2402485a7e6972b68e867413ad7a1d71add5d0336"
+  output_digest: "sha256:8fd7fc9e1adc79eec4876daaa1d9711882d3959584c92fc5c427c64ee6ecebce"
   files:
     - path: ".gds/compiled-policy.json"
       digest: "sha256:78d09606bb4168d74bce1f50ab62b46a7ded34652c6b23af1badfd26dd060e94"
     - path: ".github/workflows/gds-ci.yml"
-      digest: "sha256:1508f13759d4a238114e35d7c6ee6e0f6d2b3b09e18d8fb7eff46b534143cb73"
+      digest: "sha256:184bc5f09a65158b07fe4d6948c4d805869ddb35f9dcfaf528c5f5b4720abebb"

.github/workflows/gds-ci.yml

@@ -1,8 +1,8 @@
 # GENERATED FILE - DO NOT EDIT DIRECTLY
 # generator: gds
 # bundle: 0.4.0-dev
-# source-tree-digest: sha256:a18f15d00b467f9585fecf7ee3230f00025f69726e17135f14eb99f3036b5827
-# input-digest: sha256:88f5073a543617f2b37990db826b8777ef8c396eb658de403f60e2e480e15f62
+# source-tree-digest: sha256:66532e92cee2ba8351911491ea4d8267fe853db10ebe36559551cb21aad5f209
+# input-digest: sha256:02a7ff040caee7de0f5de1b2402485a7e6972b68e867413ad7a1d71add5d0336
 # output-digest: sha256:01fb4854784be9e4564bcc84e70786484b370879be5e5ab1dd49f8b73ea2dea4
 # edit-source:
 #   - .gds/repository.yaml

core/app/module_coverage.go

@@ -127,6 +127,23 @@ func (services *Services) CoverModules(
 			Evidence: map[string]any{"module": selected},
 		})
 	}
+	// Coverage over nothing is not coverage. Without this the command reports
+	// success having compared no module against any gate, which is
+	// indistinguishable from every module being covered -- and the estates most
+	// likely to hit it are the ones whose repositories were never declared as
+	// modules, which is exactly when someone is asking whether their gates are
+	// watched.
+	if len(data.Modules) == 0 {
+		findings = append(findings, domain.Finding{
+			Code: "GDS_MODULE_COVERAGE_SCOPE_NOT_PROVEN", Severity: domain.SeverityHigh,
+			Message: "No declared git-submodule-consumer relationship was covered, " +
+				"so no gate was compared.",
+			Evidence: map[string]any{
+				"declared_relationships": len(consumer.Relationships),
+				"repository_id":          consumer.Repository.ID,
+			},
+		})
+	}
 	return domain.NewEnvelope(command, classifyFindings(findings), data, findings...)
 }
 

core/app/module_coverage_test.go

@@ -0,0 +1,44 @@
+package app
+
+import (
+	"context"
+	"testing"
+
+	"github.com/NDDev-OpenNetwork/github-device-sync/core/domain"
+)
+
+// TestModuleCoverageOverNothingIsNotProven covers the case the command was
+// silent about. An estate whose repositories are not declared as
+// git-submodule-consumer relationships gets an empty module set, and reporting
+// success there is indistinguishable from every module being covered -- while
+// the estates most likely to hit it are exactly the ones asking whether their
+// gates are watched at all.
+//
+// This runs against the external estate fixture rather than the developer's own
+// machine. A first version of this test lived in core/cli and passed locally
+// only because a registered estate happened to be configured there; in CI the
+// command failed earlier at GDS_POLICY_ESTATE_NOT_PROVEN and never reached this
+// path, so it was green over the wrong refusal.
+func TestModuleCoverageOverNothingIsNotProven(t *testing.T) {
+	root := appTestRepositoryRoot(t)
+	runtimePath := appTestRuntimeConfig(t, root)
+	services, err := NewServices(DefaultClock)
+	if err != nil {
+		t.Fatal(err)
+	}
+	envelope := services.CoverModules(context.Background(), root, ModuleCoverageOptions{
+		GitHubReadOptions: GitHubReadOptions{RuntimeConfig: runtimePath},
+	})
+	if envelope.ExitClass == domain.ExitSuccess {
+		t.Fatalf("coverage over an empty module set reported success: %#v", envelope)
+	}
+	found := false
+	for _, finding := range envelope.Findings {
+		if finding.Code == "GDS_MODULE_COVERAGE_SCOPE_NOT_PROVEN" {
+			found = true
+		}
+	}
+	if !found {
+		t.Fatalf("no GDS_MODULE_COVERAGE_SCOPE_NOT_PROVEN finding: %#v", envelope)
+	}
+}