refactor: robust version parsing

Tries to parse given version in `ComparableVersion` disregarding
non-numeric characters. This allows parsing Docker CLI versions like
`18.06.0-dev`.

core/src/main/java/org/testcontainers/utility/ComparableVersion.java

@@ -1,22 +1,27 @@
 package org.testcontainers.utility;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import com.google.common.annotations.VisibleForTesting;
+
 import org.jetbrains.annotations.NotNull;
 
-public class ComparableVersion implements Comparable<ComparableVersion> {
+public final class ComparableVersion implements Comparable<ComparableVersion> {
 
-    private final String[] parts;
+    private final int[] parts;
 
     public static final ComparableVersion OS_VERSION = new ComparableVersion(System.getProperty("os.version"));
 
     public ComparableVersion(String version) {
-        this.parts = version.split("\\.");
+        this.parts = parseVersion(version);
     }
 
     @Override
     public int compareTo(@NotNull ComparableVersion other) {
         for (int i=0; i<Math.min(this.parts.length, other.parts.length); i++) {
-            Integer thisPart = Integer.valueOf(this.parts[i]);
-            Integer otherPart = Integer.valueOf(other.parts[i]);
+            int thisPart = this.parts[i];
+            int otherPart = other.parts[i];
             if (thisPart > otherPart) {
                 return 1;
             } else if (thisPart < otherPart) {
@@ -34,4 +39,33 @@ public boolean isLessThan(String other) {
     public boolean isGreaterThanOrEqualTo(String other) {
         return this.compareTo(new ComparableVersion(other)) >= 0;
     }
+
+    @VisibleForTesting
+    static int[] parseVersion(final String version) {
+        final List<Integer> parts = new ArrayList<>(5);
+
+        int acc = 0;
+        for (final char c : version.toCharArray()) {
+            if (c == '.') {
+                parts.add(acc);
+                acc = 0;
+            }
+
+            if (Character.isDigit(c)) {
+                acc = 10 * acc + Character.digit(c, 10);
+            }
+        }
+
+        if (acc != 0) {
+            parts.add(acc);
+        }
+
+        final int[] ret = new int[parts.size()];
+        for (int i = 0; i < ret.length; i++) {
+            ret[i] = parts.get(i);
+        }
+
+        return ret;
+    }
+
 }

core/src/test/java/org/testcontainers/utility/ComparableVersionTest.java

@@ -0,0 +1,40 @@
+package org.testcontainers.utility;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import static org.junit.Assert.assertArrayEquals;
+
+@RunWith(Parameterized.class)
+public class ComparableVersionTest {
+
+    private final int[] expected;
+    private final String given;
+
+    public ComparableVersionTest(final String given, final int[] expected) {
+        this.given = given;
+        this.expected = expected;
+    }
+
+    @Test
+    public void shouldParseVersions() {
+        assertArrayEquals(expected, ComparableVersion.parseVersion(given));
+    }
+
+    @Parameters(name = "Parsed version: {0}={1}")
+    public static Iterable<Object[]> data() {
+        return Arrays.asList(new Object[][] {
+            {"1.2.3", new int[] {1, 2, 3}},
+            {"", new int[0]},
+            {"1", new int[] {1}},
+            {"1.2.3.4.5.6.7", new int[] {1, 2, 3, 4, 5, 6, 7}},
+            {"1.2-dev", new int[] {1, 2}},
+            {"18.06.0-dev", new int[] {18, 6}},
+        });
+    }
+
+}