sbom: fix errors, improve reproducibility, tests.

- Remove/change data from bottle SBOM to avoid harming reproduciblity
- Add `schema_validation_errors` method to provide nicer test failures
- Add tests more tests for SBOM when bottling
- Cleanup SBOM tests to use more typical RSpec form and be DRYer

Library/Homebrew/sbom.rb

@@ -22,18 +22,11 @@ class SBOM
     end
     active_spec_sym = formula.active_spec_sym
 
-    homebrew_version_maybe_dev = if (match_data = HOMEBREW_VERSION.match(/^[\d.]+/))
-      suffix = "-dev" if HOMEBREW_VERSION.include?("-")
-      match_data[0] + suffix.to_s
-    else
-      HOMEBREW_VERSION
-    end
-
     attributes = {
       name:                 formula.name,
-      homebrew_version:     homebrew_version_maybe_dev,
+      homebrew_version:     HOMEBREW_VERSION,
       spdxfile:             SBOM.spdxfile(formula),
-      time:                 tab.time,
+      time:                 tab.time || Time.now,
       source_modified_time: tab.source_modified_time.to_i,
       compiler:             tab.compiler,
       stdlib:               tab.stdlib,
@@ -92,22 +85,27 @@ class SBOM
     @schema ||= JSON.parse(SCHEMA_FILE.read, freeze: true)
   end
 
-  sig { params(bottling: T::Boolean).returns(T::Boolean) }
-  def valid?(bottling: false)
+  sig { params(bottling: T::Boolean).returns(T::Array[T::Hash[String, T.untyped]]) }
+  def schema_validation_errors(bottling: false)
     unless require? "json_schemer"
       error_message = "Need json_schemer to validate SBOM, run `brew install-bundler-gems --add-groups=bottle`!"
       odie error_message if ENV["HOMEBREW_ENFORCE_SBOM"]
-      return true
+      return []
     end
 
     schemer = JSONSchemer.schema(SBOM.schema)
     data = to_spdx_sbom(bottling:)
-    return true if schemer.valid?(data)
+
+    schemer.validate(data).map { |error| error["error"] }
+  end
+
+  sig { params(bottling: T::Boolean).returns(T::Boolean) }
+  def valid?(bottling: false)
+    validation_errors = schema_validation_errors(bottling:)
+    return true if validation_errors.empty?
 
     opoo "SBOM validation errors:"
-    schemer.validate(data).to_a.each do |error|
-      puts error["error"]
-    end
+    validation_errors.each(&:puts)
 
     odie "Failed to validate SBOM against JSON schema!" if ENV["HOMEBREW_ENFORCE_SBOM"]
 
@@ -210,7 +208,7 @@ class SBOM
         filesAnalyzed:    false,
         licenseDeclared:  assert_value(nil),
         builtDate:        source_modified_time.to_s,
-        licenseConcluded: license,
+        licenseConcluded: assert_value(license),
         downloadLocation: bottle_info.fetch("url"),
         copyrightText:    assert_value(nil),
         externalRefs:     [
@@ -323,8 +321,8 @@ class SBOM
     if stdlib.present?
       compiler_info["SPDXRef-Stdlib"] = {
         SPDXID:           "SPDXRef-Stdlib",
-        name:             stdlib,
-        versionInfo:      stdlib,
+        name:             stdlib.to_s,
+        versionInfo:      stdlib.to_s,
         filesAnalyzed:    false,
         licenseDeclared:  assert_value(nil),
         licenseConcluded: assert_value(nil),
@@ -335,15 +333,21 @@ class SBOM
       }
     end
 
+    # Improve reproducibility when bottling.
+    if bottling
+      created = source_modified_time.iso8601
+      creators = ["Tool: https://github.com/Homebrew/brew"]
+    else
+      created = Time.at(time).utc.iso8601
+      creators = ["Tool: https://github.com/Homebrew/brew@#{homebrew_version}"]
+    end
+
     packages = generate_packages_json(runtime_full, compiler_info, bottling:)
     {
       SPDXID:            "SPDXRef-DOCUMENT",
       spdxVersion:       "SPDX-2.3",
       name:              "SBOM-SPDX-#{name}-#{spec_version}",
-      creationInfo:      {
-        created:  (Time.at(time).utc.iso8601 if time.present? && !bottling),
-        creators: ["Tool: https://github.com/homebrew/brew@#{homebrew_version}"],
-      },
+      creationInfo:      { created:, creators: },
       dataLicense:       "CC0-1.0",
       documentNamespace: "https://formulae.brew.sh/spdx/#{name}-#{spec_version}.json",
       documentDescribes: packages.map { |dependency| dependency[:SPDXID] },

Library/Homebrew/test/sbom_spec.rb

@@ -3,15 +3,25 @@
 require "sbom"
 
 RSpec.describe SBOM do
-  describe "#valid?" do
-    it "returns true if a minimal SBOM is valid" do
-      f = formula { url "foo-1.0" }
-      sbom = described_class.create(f, Tab.new)
-      expect(sbom).to be_valid
+  describe "#schema_validation_errors" do
+    subject(:sbom) { described_class.create(f, tab) }
+
+    before { ENV.delete("HOMEBREW_ENFORCE_SBOM") }
+
+    let(:f) { formula { url "foo-1.0" } }
+    let(:tab) { Tab.new }
+
+    it "returns true if valid" do
+      expect(sbom.schema_validation_errors).to be_empty
     end
 
-    it "returns true if a maximal SBOM is valid" do
-      f = formula do
+    it "returns true if valid when bottling" do
+      expect(sbom.schema_validation_errors(bottling: true)).to be_empty
+    end
+
+    context "with a maximal SBOM" do
+      let(:f) do
+        formula do
           homepage "https://brew.sh"
 
           url "https://brew.sh/test-0.1.tbz"
@@ -32,7 +42,8 @@ RSpec.describe SBOM do
           uses_from_macos "python" => :build
           uses_from_macos "zlib"
         end
-
+      end
+      let(:tab) do
         beanstalkd = formula "beanstalkd" do
           url "one-1.1"
 
@@ -59,21 +70,36 @@ RSpec.describe SBOM do
             "declared_directly" => true,
           }
         end
-      expect(Tab).to receive(:runtime_deps_hash).and_return(runtime_deps_hash)
+        allow(Tab).to receive(:runtime_deps_hash).and_return(runtime_deps_hash)
         tab = Tab.create(f, DevelopmentTools.default_compiler, :libcxx)
 
-      expect(Formulary).to receive(:factory).with("beanstalkd").and_return(beanstalkd)
-      expect(Formulary).to receive(:factory).with("zlib").and_return(zlib)
+        allow(Formulary).to receive(:factory).with("beanstalkd").and_return(beanstalkd)
+        allow(Formulary).to receive(:factory).with("zlib").and_return(zlib)
 
-      sbom = described_class.create(f, tab)
-      expect(sbom).to be_valid
+        tab
       end
 
-    it "returns false if an SBOM is invalid" do
-      f = formula { url "foo-1.0" }
-      sbom = described_class.create(f, Tab.new)
+      it "returns true if valid" do
+        expect(sbom.schema_validation_errors).to be_empty
+      end
+
+      it "returns true if valid when bottling" do
+        expect(sbom.schema_validation_errors(bottling: true)).to be_empty
+      end
+    end
+
+    context "with an invalid SBOM" do
+      before do
         allow(sbom).to receive(:to_spdx_sbom).and_return({}) # fake an empty SBOM
-      expect(sbom).not_to be_valid
+      end
+
+      it "returns false" do
+        expect(sbom.schema_validation_errors).not_to be_empty
+      end
+
+      it "returns false when bottling" do
+        expect(sbom.schema_validation_errors(bottling: true)).not_to be_empty
+      end
     end
   end
 end