1 files changed, 103 insertions, 0 deletions
diff --git a/integration_test.go b/integration_test.go
new file mode 100644
index 0000000..42b13a5
--- /dev/null
+++ b/integration_test.go
@@ -0,0 +1,103 @@
+//go:build integration
+// +build integration
+
+package main
+
+import (
+	"bytes"
+	_ "embed"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+
+	"github.com/alecthomas/assert/v2"
+)
+
+//go:embed testdata/package.nix
+var packageNix []byte
+
+//go:embed testdata/configuration.nix
+var configurationNix []byte
+
+func TestDiffNixPackage(t *testing.T) {
+	tempDir := t.TempDir()
+	os.WriteFile(tempDir+"/default.nix", packageNix, 0644)
+	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.3")
+	copySymlink(tempDir+"/result", tempDir+"/old-result")
+	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.4")
+
+	var sb strings.Builder
+	innerMain(&sb, tempDir+"/old-result", tempDir+"/result")
+	assert.Equal(t, sb.String(), strings.TrimLeft(`
+Version changed:
+  test-dependency: 1.2.3 -> 1.2.4
+
+  test-indirect-dependency: 1.2.3 -> 1.2.4
+`, "\n"))
+}
+
+func TestDiffNixPackageDrv(t *testing.T) {
+	tempDir := t.TempDir()
+	os.WriteFile(tempDir+"/default.nix", packageNix, 0644)
+	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.3")
+	copySymlink(tempDir+"/result", tempDir+"/old-result")
+	runIn(tempDir, "nix-build", "--argstr", "version", "1.2.4")
+
+	out, _ := runIn(tempDir, "nix-store", "--query", "--deriver", "old-result", "result")
+	lines := strings.Split(out, "\n")
+
+	var sb strings.Builder
+	innerMain(&sb, lines[0], lines[1])
+	assert.Equal(t, sb.String(), strings.TrimLeft(`
+Version changed:
+  test-dependency: 1.2.3 -> 1.2.4
+
+  test-indirect-dependency: 1.2.3 -> 1.2.4
+`, "\n"))
+}
+
+func TestDiffNixSystem(t *testing.T) {
+	tempDir := t.TempDir()
+	os.WriteFile(tempDir+"/package.nix", packageNix, 0644)
+	os.WriteFile(tempDir+"/configuration.nix", configurationNix, 0644)
+	os.WriteFile(tempDir+"/version.nix", []byte("\"1.2.3\""), 0644)
+	runIn(tempDir, "nixos-rebuild", "build", "-I", "nixos-config=configuration.nix", "-I", "pkg-version=./version.nix")
+	err := copySymlink(tempDir+"/result", tempDir+"/old-result")
+	assert.NoError(t, err)
+	os.WriteFile(tempDir+"/version.nix", []byte("\"1.2.4\""), 0644)
+	runIn(tempDir, "nixos-rebuild", "build", "-I", "nixos-config=configuration.nix", "-I", "pkg-version=./version.nix")
+
+	var sb strings.Builder
+	innerMain(&sb, tempDir+"/old-result", tempDir+"/result")
+	assert.Equal(t, sb.String(), strings.TrimLeft(`
+Version changed:
+  test-package: 1.2.3 -> 1.2.4
+  user-package: 1.2.3 -> 1.2.4
+
+  test-dependency: 1.2.3 -> 1.2.4
+  test-indirect-dependency: 1.2.3 -> 1.2.4
+`, "\n"))
+}
+
+func runIn(dir string, name string, args ...string) (string, error) {
+	cmd := exec.Command(name, args...)
+	cmd.Dir = dir
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+	out, err := cmd.Output()
+	if err != nil {
+		return "", fmt.Errorf("%s failed: %v: %s", name, err, stderr.String())
+	}
+	return string(out), nil
+}
+
+func copySymlink(src, dst string) error {
+	target, err := os.Readlink(src)
+	if err != nil {
+		return err
+	}
+
+	return os.Symlink(target, dst)
+}