fix param mutability bug, defer dryrun till full activity rendering

nb-apis/adapters-api/src/main/java/io/nosqlbench/adapters/api/activityconfig/OpsLoader.java

@@ -76,14 +76,17 @@ public class OpsLoader {
         if (srcuri != null) {
             logger.info("workload URI: '" + srcuri + "'");
         }
-        Map<String, ?> expressionParams = params == null ? Map.of() : Map.copyOf(params);
+        // Defensive copy so template processing never mutates caller-owned params
+        Map<String, Object> mutableParams =
+            (params == null) ? new java.util.LinkedHashMap<>() : new java.util.LinkedHashMap<>(params);
+        Map<String, ?> expressionParams = Map.copyOf(mutableParams);
 
         // Use TemplateContext to automatically manage template state lifecycle
         try (TemplateContext ctx = TemplateContext.enter()) {
             // PHASE 1: Rewrite TEMPLATE syntax to expr function calls
             // This converts TEMPLATE(k,v) and ${key:value} to expr paramOr() calls
             String templateRewritten = switch (fmt) {
-                case jsonnet -> evaluateJsonnet(srcuri, params); // Jsonnet doesn't need template rewriting
+                case jsonnet -> evaluateJsonnet(srcuri, mutableParams); // Jsonnet doesn't need template rewriting
                 case yaml, json, inline, stmt -> TemplateRewriter.rewrite(sourceData);
             };
 
@@ -103,7 +106,6 @@ public class OpsLoader {
             Map<String, String> templateAccesses = ctx.getAccesses();
             templateAccesses.forEach((k, v) -> {
                 layered.addTemplateVariable(k, v);
-                params.remove(k);
             });
 
             return layered;

nb-apis/adapters-api/src/test/java/io/nosqlbench/adapters/api/activityconfig/OpsLoaderTest.java

@@ -149,4 +149,25 @@ public class OpsLoaderTest {
         assertThat(result.getTemplateVariables()).containsKey("username");
     }
 
+    @Test
+    public void testTemplateProcessingDoesNotMutateParams() {
+        String yaml = """
+            ops:
+              - stmt: "value is TEMPLATE(cmd_line_param,theDefault)"
+            """;
+
+        Map<String, String> params = new HashMap<>();
+        params.put("cmd_line_param", "TheProvidedParameter");
+
+        OpsDocList first = OpsLoader.loadString(yaml, OpTemplateFormat.yaml, params, null);
+        assertThat(params).containsEntry("cmd_line_param", "TheProvidedParameter");
+        assertThat(first.getStmtDocs().get(0).getOpTemplates().get(0).getStmt())
+            .hasValue("value is TheProvidedParameter");
+
+        OpsDocList second = OpsLoader.loadString(yaml, OpTemplateFormat.yaml, params, null);
+        assertThat(params).containsEntry("cmd_line_param", "TheProvidedParameter");
+        assertThat(second.getStmtDocs().get(0).getOpTemplates().get(0).getStmt())
+            .hasValue("value is TheProvidedParameter");
+    }
+
 }

nb-engine/nb-engine-core/src/main/java/io/nosqlbench/engine/api/scenarios/NBCLIScenarioPreprocessor.java

@@ -128,7 +128,10 @@ public class NBCLIScenarioPreprocessor {
                 .first().orElseThrow();
 
             // TODO: The yaml needs to be parsed with arguments from each command independently to support template vars
-            OpsDocList scenariosYaml = OpsLoader.loadContent(yamlWithNamedScenarios, new LinkedHashMap<>(userProvidedParams));
+            // Avoid triggering dryrun modes during scenario parsing; these should apply to the final activity load
+            LinkedHashMap<String, String> paramsForScenarioParsing = new LinkedHashMap<>(userProvidedParams);
+            paramsForScenarioParsing.remove("dryrun");
+            OpsDocList scenariosYaml = OpsLoader.loadContent(yamlWithNamedScenarios, paramsForScenarioParsing);
             Scenarios scenarios = scenariosYaml.getDocScenarios();
 
             String[] nameparts = scenarioName.split("\\.",2);

nb-engine/nb-engine-core/src/test/java/io/nosqlbench/engine/api/scenarios/NBCLIScenarioPreprocessorDryrunProbe.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.nosqlbench.engine.api.scenarios;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Probe used by NBCLIScenarioPreprocessorTest to ensure dryrun does not
+ * trigger System.exit during scenario parsing.
+ */
+public class NBCLIScenarioPreprocessorDryrunProbe {
+    public static void main(String[] args) {
+        LinkedList<String> argv = new LinkedList<>();
+        argv.add("cmdline_template");
+        argv.add("the_scenario");
+        argv.add("dryrun=exprs");
+
+        NBCLIScenarioPreprocessor.rewriteScenarioCommands(argv, List.of("src/test/resources"));
+
+        System.out.println("PROBE_OK");
+        System.out.println("ARGS=" + String.join(" ", argv));
+    }
+}

nb-engine/nb-engine-core/src/test/java/io/nosqlbench/engine/api/scenarios/NBCLIScenarioPreprocessorTest.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.nosqlbench.engine.api.scenarios;
+
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.nio.charset.StandardCharsets;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@Tag("unit")
+public class NBCLIScenarioPreprocessorTest {
+
+    @Test
+    public void rewriteScenarioCommands_shouldNotTriggerDryrunDuringScenarioParsing() throws Exception {
+        String javaBin = System.getProperty("java.home") + File.separator + "bin" + File.separator + "java";
+        String classpath = System.getProperty("java.class.path");
+
+        ProcessBuilder pb = new ProcessBuilder(
+            javaBin,
+            "-cp",
+            classpath,
+            "io.nosqlbench.engine.api.scenarios.NBCLIScenarioPreprocessorDryrunProbe"
+        );
+        pb.directory(new File(System.getProperty("user.dir")));
+        pb.redirectErrorStream(true);
+
+        Process p = pb.start();
+        String output = new String(p.getInputStream().readAllBytes(), StandardCharsets.UTF_8);
+        int exit = p.waitFor();
+
+        assertThat(exit).isEqualTo(0);
+        assertThat(output).contains("PROBE_OK");
+        assertThat(output).contains("cmd_line_param=firstone");
+        assertThat(output).contains("dryrun=exprs");
+        assertThat(output).contains("run");
+    }
+}

nb-engine/nb-engine-core/src/test/resources/activities/cmdline_template.yaml

@@ -0,0 +1,11 @@
+scenarios:
+  the_scenario:
+    the_activity: run driver=stdout tags==block:the_block threads==1 cycles==1 cmd_line_param=TEMPLATE(cmd_line_param, firstone)
+blocks:
+  the_block:
+    ops:
+      the_only_op:
+        stmt: |
+          ================================================
+          The command-line-parameter is: "TEMPLATE(cmd_line_param, theDefault)".
+          ================================================