fix: update mixed case dependencies in python to be normalized (#4573)

---------
Signed-off-by: Christopher Phillips <32073428+spiffcs@users.noreply.github.com>

syft/pkg/cataloger/python/cataloger_test.go

@@ -635,6 +635,7 @@ func Test_PackageCataloger_Relationships(t *testing.T) {
 				"jinja2 @ 3.1.4 (.) [dependency-of] fastapi @ 0.111.0 (.)",
 				"jinja2 @ 3.1.4 (.) [dependency-of] starlette @ 0.37.2 (.)",
 				"markdown-it-py @ 3.0.0 (.) [dependency-of] rich @ 13.7.1 (.)",
+				"markupsafe @ 2.1.5 (.) [dependency-of] jinja2 @ 3.1.4 (.)", // MarkupSafe (mixed case) -> markupsafe
 				"mdurl @ 0.1.2 (.) [dependency-of] markdown-it-py @ 3.0.0 (.)",
 				"orjson @ 3.10.3 (.) [dependency-of] fastapi @ 0.111.0 (.)",
 				"pydantic @ 2.7.1 (.) [dependency-of] fastapi @ 0.111.0 (.)",

syft/pkg/cataloger/python/dependency.go

@@ -74,8 +74,10 @@ func isDependencyForExtra(dep pkg.PythonPoetryLockDependencyEntry) bool {
 }
 
 func packageRef(name, extra string) string {
-	cleanExtra := strings.TrimSpace(extra)
-	cleanName := strings.TrimSpace(name)
+	// normalize both package name and extra to ensure case-insensitive matching per Python packaging spec
+	// https://packaging.python.org/en/latest/specifications/name-normalization/
+	cleanName := normalize(strings.TrimSpace(name))
+	cleanExtra := normalize(strings.TrimSpace(extra))
 	if cleanExtra == "" {
 		return cleanName
 	}

syft/pkg/cataloger/python/dependency_test.go

@@ -181,6 +181,30 @@ func Test_poetryLockDependencySpecifier(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "dependency names with mixed case should be normalized",
+			p: pkg.Package{
+				Name: "dj-rest-auth",
+				Metadata: pkg.PythonPoetryLockEntry{
+					Dependencies: []pkg.PythonPoetryLockDependencyEntry{
+						{
+							Name:    "Django", // note: capital D
+							Version: ">=4.2,<6.0",
+						},
+						{
+							Name:    "djangorestframework",
+							Version: ">=3.13.0",
+						},
+					},
+				},
+			},
+			want: dependency.Specification{
+				ProvidesRequires: dependency.ProvidesRequires{
+					Provides: []string{"dj-rest-auth"},
+					Requires: []string{"django", "djangorestframework"}, // "Django" should be normalized to "django"
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -195,6 +219,38 @@ func Test_poetryLockDependencySpecifier_againstPoetryLock(t *testing.T) {
 		fixture string
 		want    []dependency.Specification
 	}{
+		{
+			name:    "case-insensitive dependency resolution",
+			fixture: "test-fixtures/poetry/case-sensitivity/poetry.lock",
+			want: []dependency.Specification{
+				// packages are in the order they appear in the lock file
+				{
+					ProvidesRequires: dependency.ProvidesRequires{
+						Provides: []string{"django"},
+						Requires: []string{"asgiref", "sqlparse"},
+					},
+				},
+				{
+					ProvidesRequires: dependency.ProvidesRequires{
+						Provides: []string{"djangorestframework"},
+						Requires: []string{"django"},
+					},
+				},
+				{
+					// dj-rest-auth depends on Django (capital D) which should resolve to django
+					ProvidesRequires: dependency.ProvidesRequires{
+						Provides: []string{"dj-rest-auth"},
+						Requires: []string{"django", "djangorestframework"}, // Django normalized to django
+					},
+					Variants: []dependency.ProvidesRequires{
+						{
+							Provides: []string{"dj-rest-auth[with-social]"},
+							Requires: []string{"django-allauth"},
+						},
+					},
+				},
+			},
+		},
 		{
 			name:    "simple dependencies with extras",
 			fixture: "test-fixtures/poetry/simple-deps/poetry.lock",
@@ -276,6 +332,64 @@ func Test_poetryLockDependencySpecifier_againstPoetryLock(t *testing.T) {
 	}
 }
 
+// Test_packageRef verifies that package references are normalized according to
+// the Python Packaging specification for names and extras:
+// https://packaging.python.org/en/latest/specifications/name-normalization/
+func Test_packageRef(t *testing.T) {
+	tests := []struct {
+		name  string
+		pkg   string
+		extra string
+		want  string
+	}{
+		{
+			name: "simple package name",
+			pkg:  "requests",
+			want: "requests",
+		},
+		{
+			name:  "package with extra",
+			pkg:   "requests",
+			extra: "security",
+			want:  "requests[security]",
+		},
+		{
+			name: "package name with mixed case",
+			pkg:  "Django",
+			want: "django",
+		},
+		{
+			name: "package name with underscores",
+			pkg:  "some_package",
+			want: "some-package",
+		},
+		{
+			name:  "package name with mixed case and extra",
+			pkg:   "Django",
+			extra: "argon2",
+			want:  "django[argon2]",
+		},
+		{
+			name:  "extra with mixed case",
+			pkg:   "package",
+			extra: "Security",
+			want:  "package[security]",
+		},
+		{
+			name:  "both with mixed case and separators",
+			pkg:   "Some_Package",
+			extra: "Dev_Extra",
+			want:  "some-package[dev-extra]",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := packageRef(tt.pkg, tt.extra)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
 func Test_extractPackageName(t *testing.T) {
 	tests := []struct {
 		name  string

syft/pkg/cataloger/python/test-fixtures/poetry/case-sensitivity/poetry.lock

@@ -0,0 +1,55 @@
+# This file is automatically @generated by Poetry and should not be edited manually.
+
+[[package]]
+name = "django"
+version = "5.2.6"
+description = "A high-level Python web framework"
+optional = false
+python-versions = ">=3.10"
+groups = ["main"]
+files = [
+    {file = "Django-5.2.6-py3-none-any.whl", hash = "sha256:example1"},
+    {file = "django-5.2.6.tar.gz", hash = "sha256:example2"},
+]
+
+[package.dependencies]
+asgiref = ">=3.8.1,<4"
+sqlparse = ">=0.3.1"
+
+[[package]]
+name = "djangorestframework"
+version = "3.16.1"
+description = "Web APIs for Django, made easy."
+optional = false
+python-versions = ">=3.9"
+groups = ["main"]
+files = [
+    {file = "djangorestframework-3.16.1-py3-none-any.whl", hash = "sha256:example3"},
+    {file = "djangorestframework-3.16.1.tar.gz", hash = "sha256:example4"},
+]
+
+[package.dependencies]
+django = ">=4.2"
+
+[[package]]
+name = "dj-rest-auth"
+version = "7.0.1"
+description = "Authentication and Registration in Django Rest Framework"
+optional = false
+python-versions = ">=3.8"
+groups = ["main"]
+files = [
+    {file = "dj-rest-auth-7.0.1.tar.gz", hash = "sha256:3f8c744cbcf05355ff4bcbef0c8a63645da38e29a0fdef3c3332d4aced52fb90"},
+]
+
+[package.dependencies]
+Django = ">=4.2,<6.0"
+djangorestframework = ">=3.13.0"
+
+[package.extras]
+with-social = ["django-allauth[socialaccount] (>=64.0.0)"]
+
+[metadata]
+lock-version = "2.1"
+python-versions = "^3.10"
+content-hash = "example"