fix(cli): resolve CLI-001 — honor SCADALINK_FORMAT and config-file format precedence

tests/ScadaLink.CLI.Tests/FormatResolutionTests.cs

@@ -0,0 +1,54 @@
+using System.CommandLine;
+using ScadaLink.CLI;
+using ScadaLink.CLI.Commands;
+
+namespace ScadaLink.CLI.Tests;
+
+public class FormatResolutionTests
+{
+    private static (Option<string> formatOption, RootCommand root) BuildHarness()
+    {
+        var formatOption = new Option<string>("--format") { Recursive = true };
+        var root = new RootCommand();
+        root.Add(formatOption);
+        return (formatOption, root);
+    }
+
+    [Fact]
+    public void ResolveFormat_ExplicitFlag_OverridesConfig()
+    {
+        var (formatOption, root) = BuildHarness();
+        var result = root.Parse(new[] { "--format", "table" });
+        var config = new CliConfig { DefaultFormat = "json" };
+
+        var format = CommandHelpers.ResolveFormat(result, formatOption, config);
+
+        Assert.Equal("table", format);
+    }
+
+    [Fact]
+    public void ResolveFormat_FlagAbsent_UsesConfigDefaultFormat()
+    {
+        // Regression for CLI-001: when --format is not supplied, the config-file /
+        // env-var DefaultFormat must be honoured instead of always falling back to "json".
+        var (formatOption, root) = BuildHarness();
+        var result = root.Parse(Array.Empty<string>());
+        var config = new CliConfig { DefaultFormat = "table" };
+
+        var format = CommandHelpers.ResolveFormat(result, formatOption, config);
+
+        Assert.Equal("table", format);
+    }
+
+    [Fact]
+    public void ResolveFormat_FlagAbsent_AndNoConfig_DefaultsToJson()
+    {
+        var (formatOption, root) = BuildHarness();
+        var result = root.Parse(Array.Empty<string>());
+        var config = new CliConfig { DefaultFormat = "json" };
+
+        var format = CommandHelpers.ResolveFormat(result, formatOption, config);
+
+        Assert.Equal("json", format);
+    }
+}