Merge pull request #780 from mvanhorn/feat/526-env-placeholder-resolution

Resolve property placeholders in target-env files

Author: nirmalchandra

core/src/main/java/org/jsmart/zerocode/core/di/main/ApplicationMainModule.java

@@ -2,8 +2,11 @@
 
 import com.google.inject.AbstractModule;
 import com.google.inject.name.Names;
+import java.util.Map;
 import java.util.Properties;
 import java.util.logging.Logger;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import org.jsmart.zerocode.core.di.module.CsvParserModule;
 import org.jsmart.zerocode.core.di.module.GsonModule;
 import org.jsmart.zerocode.core.di.module.HttpClientModule;
@@ -30,13 +33,16 @@
 import org.jsmart.zerocode.core.runner.ZeroCodeMultiStepsScenarioRunner;
 import org.jsmart.zerocode.core.runner.ZeroCodeMultiStepsScenarioRunnerImpl;
 
+import static org.jsmart.zerocode.core.utils.EnvUtils.getEnvValueString;
 import static org.jsmart.zerocode.core.utils.PropertiesProviderUtils.checkAndLoadOldProperties;
 import static org.jsmart.zerocode.core.utils.PropertiesProviderUtils.loadAbsoluteProperties;
 import static org.jsmart.zerocode.core.utils.SmartUtils.isValidAbsolutePath;
 
 public class ApplicationMainModule extends AbstractModule {
     private static final Logger LOGGER = Logger.getLogger(ApplicationMainModule.class.getName());
 
+    private static final Pattern ENV_PLACEHOLDER_PATTERN = Pattern.compile("\\$\\{([^}]+)\\}");
+
     private final String serverEnv;
 
     public ApplicationMainModule(String serverEnv) {
@@ -79,7 +85,7 @@ public Properties getProperties(String host) {
         final Properties properties = new Properties();
 
         if(isValidAbsolutePath(host)){
-            return loadAbsoluteProperties(host, properties);
+            return resolveEnvPlaceholders(loadAbsoluteProperties(host, properties));
         }
 
         try {
@@ -96,7 +102,54 @@ public Properties getProperties(String host) {
             throw new RuntimeException("could not read the target-env properties file --" + host + "-- from the classpath.");
         }
 
+        return resolveEnvPlaceholders(properties);
+    }
+
+    /**
+     * Resolves any {@code ${name}} placeholders found in the loaded property values against
+     * system properties and OS environment variables (in that order, via
+     * {@link org.jsmart.zerocode.core.utils.EnvUtils#getEnvValueString(String)}).
+     * <p>
+     * This lets a target-env properties file reference values supplied on the command line, e.g.
+     * <pre>
+     *     db.username=${db.username}
+     * </pre>
+     * run with {@code -Ddb.username=alice} so the injected value becomes {@code alice}.
+     * <p>
+     * A placeholder whose name resolves to no system property or env var is left untouched, so
+     * files that legitimately contain {@code ${...}} for downstream tooling are not corrupted.
+     * Values without any placeholder are returned unchanged.
+     */
+    public Properties resolveEnvPlaceholders(Properties properties) {
+        if (properties == null) {
+            return null;
+        }
+
+        for (Map.Entry<Object, Object> entry : properties.entrySet()) {
+            Object value = entry.getValue();
+            if (value instanceof String) {
+                properties.setProperty((String) entry.getKey(), resolvePlaceholders((String) value));
+            }
+        }
+
         return properties;
     }
 
+    private static String resolvePlaceholders(String value) {
+        Matcher matcher = ENV_PLACEHOLDER_PATTERN.matcher(value);
+        StringBuffer resolved = new StringBuffer();
+
+        while (matcher.find()) {
+            String placeholderName = matcher.group(1);
+            String replacement = getEnvValueString(placeholderName);
+
+            // Leave the placeholder literally in place when it cannot be resolved (backward compatible).
+            String token = replacement != null ? replacement : matcher.group(0);
+            matcher.appendReplacement(resolved, Matcher.quoteReplacement(token));
+        }
+        matcher.appendTail(resolved);
+
+        return resolved.toString();
+    }
+
 }

core/src/test/java/org/jsmart/zerocode/core/di/ApplicationMainModuleTest.java

@@ -3,9 +3,11 @@
 import com.google.inject.AbstractModule;
 import com.google.inject.Inject;
 import com.google.inject.name.Named;
+import java.util.Properties;
 import org.jsmart.zerocode.core.di.main.ApplicationMainModule;
 import org.jsmart.zerocode.core.guice.ZeroCodeGuiceTestRule;
 import org.jsmart.zerocode.core.utils.SmartUtils;
+import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
@@ -49,4 +51,40 @@ public void willInject_host() throws Exception {
         assertThat(host, is("http://localhost-test"));
     }
 
+    @After
+    public void clearTestSystemProperties() {
+        System.clearProperty("zc.test.host");
+    }
+
+    @Test
+    public void willResolveSystemPropertyPlaceholder() throws Exception {
+        System.setProperty("zc.test.host", "http://resolved-host");
+
+        ApplicationMainModule module = new ApplicationMainModule("config_hosts_test.properties");
+        Properties properties = module.getProperties("config_hosts_test.properties");
+
+        assertThat(properties.getProperty("placeholder.resolved.host"), is("http://resolved-host"));
+    }
+
+    @Test
+    public void willKeepUnresolvedPlaceholderLiteral() throws Exception {
+        ApplicationMainModule module = new ApplicationMainModule("config_hosts_test.properties");
+        Properties properties = module.getProperties("config_hosts_test.properties");
+
+        // No matching system property / env var -> placeholder is preserved verbatim (backward compatible).
+        assertThat(properties.getProperty("placeholder.unresolved.host"), is("${zc.test.absent.host}"));
+    }
+
+    @Test
+    public void willReturnPlainPropertyUnchanged() throws Exception {
+        ApplicationMainModule module = new ApplicationMainModule("config_hosts_test.properties");
+
+        Properties input = new Properties();
+        input.setProperty("plain.key", "plain-value-without-placeholder");
+
+        Properties resolved = module.resolveEnvPlaceholders(input);
+
+        assertThat(resolved.getProperty("plain.key"), is("plain-value-without-placeholder"));
+    }
+
 }

core/src/test/resources/config_hosts_test.properties

@@ -4,3 +4,7 @@ web.application.endpoint.port=8820
 
 # Google Map Service Context
 web.application.endpoint.context=/google-map-services
+
+# Placeholders resolved against system properties / OS env vars at load time
+placeholder.resolved.host=${zc.test.host}
+placeholder.unresolved.host=${zc.test.absent.host}