terraform test: Fix crash when referencing variables within the file …

…level variable block

internal/backend/local/test.go

@@ -1023,7 +1023,7 @@ func (runner *TestFileRunner) GetVariables(config *configs.Config, run *modulete
 	values := make(terraform.InputValues)
 
 	// First, let's look at the global variables.
-	for name, value := range runner.globalVariables {
+	for name, variable := range runner.globalVariables {
 		if !relevantVariables[name] {
 			// Then this run block doesn't need this value.
 			continue
@@ -1039,9 +1039,22 @@ func (runner *TestFileRunner) GetVariables(config *configs.Config, run *modulete
 			parsingMode = cfg.ParsingMode
 		}
 
-		var valueDiags tfdiags.Diagnostics
-		values[name], valueDiags = value.ParseVariableValue(parsingMode)
+		value, valueDiags := variable.ParseVariableValue(parsingMode)
 		diags = diags.Append(valueDiags)
+		if diags.HasErrors() {
+			// We still add a value for this variable even though we couldn't
+			// parse it as we don't want to compound errors later. For example,
+			// the system would report this variable didn't have a value which
+			// would confuse the user because it does have a value, it's just
+			// not a valid value. We have added the diagnostics so the user
+			// will be informed about the error, and the test won't run. We'll
+			// just report only the relevant errors.
+			values[name] = &terraform.InputValue{
+				Value: cty.NilVal,
+			}
+			continue
+		}
+		values[name] = value
 	}
 
 	// Second, we'll check the run level variables.

internal/command/test_test.go

@@ -227,6 +227,11 @@ func TestTest_Runs(t *testing.T) {
 			expectedOut: "1 passed, 0 failed.",
 			code:        0,
 		},
+		"global_var_refs": {
+			expectedOut: "2 failed, 1 skipped.",
+			expectedErr: "Variables may not be used here.",
+			code:        1,
+		},
 	}
 	for name, tc := range tcs {
 		t.Run(name, func(t *testing.T) {
@@ -281,7 +286,7 @@ func TestTest_Runs(t *testing.T) {
 			}
 
 			if !strings.Contains(output.Stdout(), tc.expectedOut) {
-				t.Errorf("output didn't contain expected string:\n\n%s", output.All())
+				t.Errorf("output didn't contain expected string:\n\n%s", output.Stdout())
 			}
 
 			if !strings.Contains(output.Stderr(), tc.expectedErr) {

internal/command/testdata/test/global_var_refs/environment_variable.tftest.hcl

@@ -0,0 +1,6 @@
+
+variables {
+  input = var.env_var_input
+}
+
+run "execute" {}

internal/command/testdata/test/global_var_refs/main.tf

@@ -0,0 +1,7 @@
+variable "input" {
+  type = string
+}
+
+output "value" {
+  value = var.input
+}

internal/command/testdata/test/global_var_refs/run_block_output.tftest.hcl

@@ -0,0 +1,17 @@
+
+variables {
+  input = var.setup.value
+}
+
+run "setup" {
+  variables {
+    input = "hello"
+  }
+}
+
+run "execute" {
+  assert {
+    condition     = output.value == "hello"
+    error_message = "bad output value"
+  }
+}