test: Add proxy e2e test (#348)

* test: Add proxy e2e test

* fix: Code review fixes

* test: Add dependency cooldown skip list test case

test/proxye2e/runner.go

@@ -0,0 +1,70 @@
+package proxye2e
+
+import (
+	"testing"
+
+	"github.com/safedep/pmg/config"
+)
+
+// TestCase is one end-to-end scenario. Config mutates the global PMG config for
+// the case; Setup registers fixtures and verdicts; Exec drives traffic; Assert
+// verifies the outcome.
+type TestCase struct {
+	Name           string
+	PinnedVersions map[string]string
+	Config         func(rc *config.RuntimeConfig)
+	Setup          func(h *Harness)
+	Exec           func(h *Harness) ExecResult
+	Assert         func(t *testing.T, h *Harness, result ExecResult)
+}
+
+// RunCases runs each case serially. Serial execution is required because the
+// interceptors read the global config singleton at request time, which the
+// runner mutates per case.
+func RunCases(t *testing.T, cases []TestCase) {
+	for _, tc := range cases {
+		t.Run(tc.Name, func(t *testing.T) {
+			applyConfig(t, tc.Config)
+
+			h := New(t, WithPinnedVersions(tc.PinnedVersions))
+			defer h.Close()
+
+			if tc.Setup != nil {
+				tc.Setup(h)
+			}
+
+			var result ExecResult
+			if tc.Exec != nil {
+				result = tc.Exec(h)
+			}
+
+			if tc.Assert != nil {
+				tc.Assert(t, h, result)
+			}
+		})
+	}
+}
+
+// applyConfig resets the security-relevant config fields to a known hermetic
+// baseline, applies the case override, then restores the original on cleanup so
+// a developer's on-disk config never leaks into a case.
+func applyConfig(t *testing.T, override func(rc *config.RuntimeConfig)) {
+	t.Helper()
+
+	rc := config.Get()
+	saved := *rc
+	t.Cleanup(func() { *rc = saved })
+
+	rc.InsecureInstallation = false
+	rc.Config.Paranoid = false
+	rc.Config.TrustedPackages = nil
+	rc.Config.DependencyCooldown = config.DependencyCooldownConfig{}
+
+	if override != nil {
+		override(rc)
+	}
+
+	if err := config.PreprocessTrustedPackages(&rc.Config); err != nil {
+		t.Fatalf("failed to preprocess trusted packages: %v", err)
+	}
+}