OS.detectPlatform can now take a Function<List<String>, String> which lets you control process execution when detecting the OS.

Author: nedtwigg

CHANGES.md

@@ -1,6 +1,8 @@
 # DurianSwt releases
 
 ## [Unreleased]
+### Added
+- `OS.detectPlatform` can now take a `Function<List<String>, String>` which lets you control process execution when detecting the OS. ([#26](https://github.com/diffplug/durian-swt/pull/26))
 
 ## [4.2.2] - 2023-10-26
 ### Fixed

durian-swt.os/src/main/java/com/diffplug/common/swt/os/OS.java

@@ -21,6 +21,7 @@
 import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Locale;
 import java.util.function.Function;
 
@@ -112,12 +113,28 @@ public static OS getRunning() {
 
 	/** Eagerly detects the native and running JVM properties. */
 	public static void detectPlatform(Function<String, String> systemProperty, Function<String, String> environmentVariable) {
+		detectPlatform(systemProperty, environmentVariable, OS::exec);
+	}
+
+	/** Eagerly detects the native and running JVM properties. */
+	public static void detectPlatform(Function<String, String> systemProperty, Function<String, String> environmentVariable, Function<List<String>, String> executeCommand) {
 		if (NATIVE_OS == null) {
-			NATIVE_OS = calculateNative(systemProperty, environmentVariable);
+			NATIVE_OS = calculateNative(systemProperty, environmentVariable, executeCommand);
 			RUNNING_OS = calculateRunning(systemProperty);
 		}
 	}
 
+	private static String exec(List<String> cmd) {
+		try {
+			Process process = Runtime.getRuntime().exec(cmd.toArray(new String[0]));
+			ByteArrayOutputStream output = new ByteArrayOutputStream();
+			drain(process.getInputStream(), output);
+			return new String(output.toByteArray(), StandardCharsets.UTF_8);
+		} catch (IOException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
 	private static void detectPlatform() {
 		if (NATIVE_OS == null) {
 			detectPlatform(System::getProperty, System::getenv);
@@ -127,13 +144,13 @@ private static void detectPlatform() {
 	private static OS NATIVE_OS;
 
 	/** Calculates the native OS. */
-	private static OS calculateNative(Function<String, String> systemProperty, Function<String, String> environmentVariable) {
+	private static OS calculateNative(Function<String, String> systemProperty, Function<String, String> environmentVariable, Function<List<String>, String> executeCommand) {
 		String os_name = systemProperty.apply("os.name").toLowerCase(Locale.getDefault());
 		boolean isWin = os_name.contains("win");
 		boolean isMac = os_name.contains("mac");
 		boolean isLinux = Arrays.asList("nix", "nux", "aix").stream().anyMatch(os_name::contains);
 		if (isMac) {
-			return exec("uname", "-a").contains("_ARM64_") ? MAC_silicon : MAC_x64;
+			return executeCommand.apply(List.of("uname", "-a")).contains("_ARM64_") ? MAC_silicon : MAC_x64;
 		} else if (isWin) {
 			boolean is64bit = environmentVariable.apply("ProgramFiles(x86)") != null;
 			return is64bit ? WIN_x64 : WIN_x86;
@@ -154,17 +171,6 @@ private static OS calculateNative(Function<String, String> systemProperty, Funct
 		}
 	}
 
-	private static String exec(String... cmd) {
-		try {
-			Process process = Runtime.getRuntime().exec(cmd);
-			ByteArrayOutputStream output = new ByteArrayOutputStream();
-			drain(process.getInputStream(), output);
-			return new String(output.toByteArray(), StandardCharsets.UTF_8);
-		} catch (IOException e) {
-			throw new RuntimeException(e);
-		}
-	}
-
 	private static void drain(InputStream input, OutputStream output) throws IOException {
 		byte[] buf = new byte[1024];
 		int numRead;