testing framework: introduce test command optional flags (#33504)

* testing framework: introduce test command optional flags

* address consistency checks

internal/command/arguments/test.go

@@ -0,0 +1,58 @@
+package arguments
+
+import "github.com/hashicorp/terraform/internal/tfdiags"
+
+// Test represents the command-line arguments for the test command.
+type Test struct {
+	// Filter contains a list of test files to execute. If empty, all test files
+	// will be executed.
+	Filter []string
+
+	// TestDirectory allows the user to override the directory that the test
+	// command will use to discover test files, defaults to "tests". Regardless
+	// of the value here, test files within the configuration directory will
+	// always be discovered.
+	TestDirectory string
+
+	// ViewType specifies which output format to use: human or JSON.
+	ViewType ViewType
+
+	// You can specify common variables for all tests from the command line.
+	Vars *Vars
+
+	// Verbose tells the test command to print out the plan either in
+	// human-readable format or JSON for each run step depending on the
+	// ViewType.
+	Verbose bool
+}
+
+func ParseTest(args []string) (*Test, tfdiags.Diagnostics) {
+	var diags tfdiags.Diagnostics
+
+	test := Test{
+		Vars: new(Vars),
+	}
+
+	var jsonOutput bool
+	cmdFlags := extendedFlagSet("test", nil, nil, test.Vars)
+	cmdFlags.Var((*flagStringSlice)(&test.Filter), "filter", "filter")
+	cmdFlags.StringVar(&test.TestDirectory, "test-directory", "tests", "test-directory")
+	cmdFlags.BoolVar(&jsonOutput, "json", false, "json")
+	cmdFlags.BoolVar(&test.Verbose, "verbose", false, "verbose")
+
+	if err := cmdFlags.Parse(args); err != nil {
+		diags = diags.Append(tfdiags.Sourceless(
+			tfdiags.Error,
+			"Failed to parse command-line flags",
+			err.Error()))
+	}
+
+	switch {
+	case jsonOutput:
+		test.ViewType = ViewJSON
+	default:
+		test.ViewType = ViewHuman
+	}
+
+	return &test, diags
+}