tests/opencode: expand tests for agents / commands

Include various tests for the agents and command file generation and
different ways of configuring it.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

tests/modules/programs/opencode/agents-inline.nix

@@ -0,0 +1,37 @@
+{
+  programs.opencode = {
+    enable = true;
+    agents = {
+      code-reviewer = ''
+        # Code Reviewer Agent
+
+        You are a senior software engineer specializing in code reviews.
+        Focus on code quality, security, and maintainability.
+
+        ## Guidelines
+        - Review for potential bugs and edge cases
+        - Check for security vulnerabilities
+        - Ensure code follows best practices
+        - Suggest improvements for readability and performance'';
+      documentation = ''
+        # Documentation Agent
+
+        You are a technical writer who creates clear, comprehensive documentation.
+        Focus on user-friendly explanations and examples.
+
+        ## Guidelines
+        - Write clear, concise documentation
+        - Include practical examples
+        - Use proper formatting and structure
+        - Consider the target audience'';
+    };
+  };
+  nmt.script = ''
+    assertFileExists home-files/.config/opencode/agent/code-reviewer.md
+    assertFileExists home-files/.config/opencode/agent/documentation.md
+    assertFileContent home-files/.config/opencode/agent/code-reviewer.md \
+      ${./code-reviewer-agent.md}
+    assertFileContent home-files/.config/opencode/agent/documentation.md \
+      ${./documentation-agent.md}
+  '';
+}