fix(testrun): preflight resolves adb through the sdk, not just PATH

internal/testrun/preflight.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 	"os/exec"
+
+	"github.com/priyanshujain/sanderling/internal/android"
 )
 
 // Preflight runs platform-specific host checks before sidecar/driver setup.
@@ -18,7 +20,15 @@ func Preflight(ctx context.Context, platform string) error {
 
 type preflightFunc func(name string) error
 
+// preflightCheck resolves adb through the same helper every adb call in a run
+// uses, so a host whose SDK is only reachable through $ANDROID_HOME or a
+// standard install location is not turned away here and then driven fine by
+// the rest of the pipeline.
 func preflightCheck(name string) error {
+	if name == "adb" {
+		_, err := android.AdbBinary()
+		return err
+	}
 	if _, err := exec.LookPath(name); err != nil {
 		return fmt.Errorf("%s not found on PATH: %w", name, err)
 	}

internal/testrun/preflight_test.go

@@ -3,6 +3,8 @@ package testrun
 import (
 	"context"
 	"errors"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 )
@@ -49,6 +51,33 @@ func TestPreflight_AndroidNeedsAdbAndJava(t *testing.T) {
 	}
 }
 
+// Every adb call in an android run resolves through $ANDROID_HOME and the
+// standard SDK locations, so a preflight that only looks at PATH turns away a
+// host the run itself would drive.
+func TestPreflight_AndroidAcceptsAdbUnderAndroidHome(t *testing.T) {
+	sdk := t.TempDir()
+	writeExecutable(t, filepath.Join(sdk, "platform-tools", "adb"))
+	pathDirectory := t.TempDir()
+	writeExecutable(t, filepath.Join(pathDirectory, "java"))
+	t.Setenv("PATH", pathDirectory)
+	t.Setenv("ANDROID_HOME", sdk)
+	t.Setenv("ANDROID_SDK_ROOT", "")
+
+	if err := Preflight(context.Background(), "android"); err != nil {
+		t.Fatalf("Preflight with adb under $ANDROID_HOME: %v", err)
+	}
+}
+
+func writeExecutable(t *testing.T, path string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir %s: %v", filepath.Dir(path), err)
+	}
+	if err := os.WriteFile(path, nil, 0o755); err != nil {
+		t.Fatalf("write %s: %v", path, err)
+	}
+}
+
 func TestPreflight_iOSNeedsXcrun(t *testing.T) {
 	check := func(name string) error {
 		if name == "xcrun" {