Cleaning up some comments, adding unit test for get_iccid()

spec/utisl_spec.lua

@@ -34,6 +34,72 @@ describe("Skyweave Utility Functions Module", function()
 
   end)
 
+  describe("Skyweave ICCID Retrieval", function()
+  
+    -- This block runs before each test ('it' block).
+    -- It's used to set up our mock environment.
+    before_each(function()
+      -- Create a backup of the original command executor.
+      -- This ensures we do not permanently damage the original scripture.
+      _G.original_execute_command = utils.execute_command
+    end)
+
+    -- This block runs after each test.
+    -- It restores the original function, ensuring our tests do not interfere with each other.
+    after_each(function()
+      utils.execute_command = _G.original_execute_command
+      _G.original_execute_command = nil
+    end)
+
+    it("should correctly decode a valid qmicli output", function()
+
+      -- 1. Define the simulated raw output from a successful qmicli invocation.
+      local mock_qmicli_output = "QMI-Client: Synchronous call... \n" ..
+                                "[/dev/cdc-wdm0] UIM transparent read result: \n" ..
+                                "Read result:\n" ..
+                                "\t'89:01:41:03:27:25:30:79:07:87:f9'\n"
+      
+      -- 2. Mock the command executor to return our simulated data.
+      utils.execute_command = function(command)
+        assert.are.equal("qmicli -d /dev/cdc-wdm0 --uim-read-transparent=0x3F00,0x2FE2", command)
+        return mock_qmicli_output
+      end
+
+      -- 3. Execute the function under test.
+      local iccid, err = utils.get_sim_iccid()
+
+      -- 4. Assert the expected outcome.
+      assert.is_nil(err)
+      assert.are.equal("981014307252039770789f", iccid)
+    end)
+
+    it("should return an error on nil or empty command output", function()
+      -- 1. Mock the command executor to return nil.
+      utils.execute_command = function(command)
+        return nil
+      end
+
+      -- 2. Execute and assert.
+      local iccid, err = utils.get_sim_iccid()
+      assert.is_nil(iccid)
+      assert.are.equal("No output from qmicli command", err)
+    end)
+
+    it("should return an error if the raw data cannot be parsed", function()
+      -- 1. Mock a response that lacks the 'Read result:' scripture.
+      local malformed_output = "QMI-Client: Call failed: QMI protocol error"
+      utils.execute_command = function(command)
+        return malformed_output
+      end
+
+      -- 2. Execute and assert.
+      local iccid, err = utils.get_sim_iccid()
+      assert.is_nil(iccid)
+      assert.are.equal("Failed to parse raw ICCID data from qmicli output", err)
+    end)
+
+  end)
+
   -- more 'describe' blocks here to test other functions in utils.lua
 
 end)