diff --git a/CLAUDE.md b/CLAUDE.md
index c2a6f82ff..0f6d148eb 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -259,6 +259,8 @@ Code reviews are required for all submissions via GitHub pull requests.
 - I do not want you to be in the co-author signoff
 - when the schema is changed, run make generate, do not create a migration explicitly
 - If you are writing go code, adhere to best practices such as the ones in effective-go, or others. This could include, error handling patterns, interface design, package organization, concurrency patterns, etc.
+- When writing tests, use table-driven tests whenever possible
+- When implementing new functionality, follow TDD: write failing tests first, then implement the code to make them pass
 - do not change previous migrations, they are immutable
 - if you add any new dependency to a constructor, remember to run wire ./...
 - when adding new inedexes, make sure to update the generated sql migraiton files and make them CREATE INDEX CONCURRENTLY and set -- atlas:txmode none at the top
@@ -272,3 +274,4 @@ Code reviews are required for all submissions via GitHub pull requests.
 - any call to authorization Enforce done from the biz or svc layer must be done using biz.AuthzUseCase
 - if you modify a schema, remember to run `make migration_sync`
 - after changing Helm chart source code (`deployment/chainloop/`), bump the **patch** version (not minor, not major) in the chart's `Chart.yaml`
+- when asked to create a GitHub issue, create it in the `chainloop-dev/chainloop` repository
diff --git a/pkg/attestation/crafter/collector_prmetadata.go b/pkg/attestation/crafter/collector_prmetadata.go
index f683a2116..2d75cc8d5 100644
--- a/pkg/attestation/crafter/collector_prmetadata.go
+++ b/pkg/attestation/crafter/collector_prmetadata.go
@@ -68,20 +68,13 @@ func (c *PRMetadataCollector) Collect(ctx context.Context, cr *Crafter, attestat
 		return fmt.Errorf("marshaling PR/MR metadata: %w", err)
 	}
 
-	materialName := fmt.Sprintf("pr-metadata-%s", metadata.Number)
-	tmpFile, err := os.CreateTemp("", fmt.Sprintf("%s-*.json", materialName))
+	materialName, tmpFile, err := createPRMetadataTempFile(metadata.Number, jsonData)
 	if err != nil {
-		return fmt.Errorf("creating temp file: %w", err)
-	}
-	defer os.Remove(tmpFile.Name())
-
-	if _, err := tmpFile.Write(jsonData); err != nil {
-		tmpFile.Close()
-		return fmt.Errorf("writing temp file: %w", err)
+		return fmt.Errorf("creating PR metadata temp file: %w", err)
 	}
-	tmpFile.Close()
+	defer os.Remove(tmpFile)
 
-	if _, err := cr.AddMaterialContractFree(ctx, attestationID, schemaapi.CraftingSchema_Material_CHAINLOOP_PR_INFO.String(), materialName, tmpFile.Name(), casBackend, nil); err != nil {
+	if _, err := cr.AddMaterialContractFree(ctx, attestationID, schemaapi.CraftingSchema_Material_CHAINLOOP_PR_INFO.String(), materialName, tmpFile, casBackend, nil); err != nil {
 		return fmt.Errorf("adding PR/MR metadata material: %w", err)
 	}
 
@@ -89,3 +82,26 @@ func (c *PRMetadataCollector) Collect(ctx context.Context, cr *Crafter, attestat
 
 	return nil
 }
+
+// createPRMetadataTempFile creates a temp file with the PR metadata JSON content
+// and returns the material name and the temp file path.
+func createPRMetadataTempFile(prNumber string, data []byte) (materialName string, filePath string, err error) {
+	materialName = fmt.Sprintf("pr-metadata-%s", prNumber)
+
+	tmpFile, err := os.CreateTemp("", fmt.Sprintf("%s-*.json", materialName))
+	if err != nil {
+		return "", "", fmt.Errorf("creating temp file: %w", err)
+	}
+
+	if _, err := tmpFile.Write(data); err != nil {
+		tmpFile.Close()
+		os.Remove(tmpFile.Name())
+		return "", "", fmt.Errorf("writing temp file: %w", err)
+	}
+	if err := tmpFile.Close(); err != nil {
+		os.Remove(tmpFile.Name())
+		return "", "", fmt.Errorf("closing temp file: %w", err)
+	}
+
+	return materialName, tmpFile.Name(), nil
+}
diff --git a/pkg/attestation/crafter/collector_prmetadata_test.go b/pkg/attestation/crafter/collector_prmetadata_test.go
new file mode 100644
index 000000000..0ed4ca310
--- /dev/null
+++ b/pkg/attestation/crafter/collector_prmetadata_test.go
@@ -0,0 +1,66 @@
+//
+// Copyright 2026 The Chainloop Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package crafter
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCreatePRMetadataTempFile(t *testing.T) {
+	tests := []struct {
+		name           string
+		prNumber       string
+		wantMaterial   string
+		wantFilePrefix string
+	}{
+		{
+			name:           "numeric PR number",
+			prNumber:       "123",
+			wantMaterial:   "pr-metadata-123",
+			wantFilePrefix: "pr-metadata-123-",
+		},
+		{
+			name:           "large PR number",
+			prNumber:       "99999",
+			wantMaterial:   "pr-metadata-99999",
+			wantFilePrefix: "pr-metadata-99999-",
+		},
+		{
+			name:           "single digit PR number",
+			prNumber:       "1",
+			wantMaterial:   "pr-metadata-1",
+			wantFilePrefix: "pr-metadata-1-",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			materialName, filePath, err := createPRMetadataTempFile(tc.prNumber, []byte(`{"test": true}`))
+			require.NoError(t, err)
+			defer os.Remove(filePath)
+
+			assert.Equal(t, tc.wantMaterial, materialName)
+			assert.Equal(t, ".json", filepath.Ext(filePath))
+			assert.True(t, strings.HasPrefix(filepath.Base(filePath), tc.wantFilePrefix))
+		})
+	}
+}
diff --git a/pkg/attestation/crafter/prmetadata_test.go b/pkg/attestation/crafter/prmetadata_test.go
index 472234b2f..1e6636839 100644
--- a/pkg/attestation/crafter/prmetadata_test.go
+++ b/pkg/attestation/crafter/prmetadata_test.go
@@ -1,5 +1,5 @@
 //
-// Copyright 2024-2025 The Chainloop Authors.
+// Copyright 2024-2026 The Chainloop Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.