Add force flag for integration testing

Also don't return unexpected errors from the function. It's not that the caller would do anything with unexpected errors, it's just going to fallback to the default behavior

Author: ofalvai

toolprovider/mise/install.go

@@ -3,6 +3,7 @@ package mise
 import (
 	"errors"
 	"fmt"
+	"os"
 
 	"github.com/bitrise-io/bitrise/v2/log"
 	"github.com/bitrise-io/bitrise/v2/toolprovider/mise/execenv"
@@ -14,7 +15,7 @@ func installRequest(toolRequest provider.ToolRequest, useNix bool) provider.Tool
 	if useNix {
 		return provider.ToolRequest{
 			// Use Mise's backend plugin convention of pluginID:toolID
-			ToolName:           provider.ToolID(fmt.Sprintf("%s:%s", nixpkgs.PluginName,toolRequest.ToolName)),
+			ToolName:           provider.ToolID(fmt.Sprintf("%s:%s", nixpkgs.PluginName, toolRequest.ToolName)),
 			UnparsedVersion:    toolRequest.UnparsedVersion,
 			ResolutionStrategy: toolRequest.ResolutionStrategy,
 			PluginURL:          nil, // Not relevant when using nixpkgs backend plugin
@@ -24,29 +25,41 @@ func installRequest(toolRequest provider.ToolRequest, useNix bool) provider.Tool
 	}
 }
 
-func (m *MiseToolProvider) canBeInstalledWithNix(tool provider.ToolRequest) (bool, error) {
+func canBeInstalledWithNix(tool provider.ToolRequest, execEnv execenv.ExecEnv) bool {
 	if !nixpkgs.ShouldUseBackend(tool) {
-		return false, nil
+		return false
 	}
 
-	output, err := m.ExecEnv.RunMisePlugin("install", nixpkgs.PluginName, nixpkgs.PluginGitURL)
+	// Force switch for integration testing. No fallback to regular install when this is active. This makes failures explicit.
+	forceNix := os.Getenv("BITRISE_TOOLSETUP_FAST_INSTALL_FORCE") == "1"
+
+	_, err := execEnv.RunMisePlugin("install", nixpkgs.PluginName, nixpkgs.PluginGitURL)
 	if err != nil {
-		return false, fmt.Errorf("install %s: %s", nixpkgs.PluginGitURL, output)
+		if forceNix {
+			return true
+		}
+		log.Warnf("Error while installing nixpkgs plugin (%s). Falling back to core plugin installation.", nixpkgs.PluginGitURL, err)
+		return false
 	}
 
 	nameWithBackend := provider.ToolID(fmt.Sprintf("nixpkgs:%s", tool.ToolName))
-
-	available, err := m.versionExists(nameWithBackend, tool.UnparsedVersion)
+	available, err := versionExists(execEnv, nameWithBackend, tool.UnparsedVersion)
 	if err != nil {
+		if forceNix {
+			return true
+		}
 		log.Warnf("Error while checking nixpkgs index for %s@%s: %v. Falling back to core plugin installation.", tool.ToolName, tool.UnparsedVersion, err)
-		return false, nil
+		return false
 	}
 	if !available {
+		if forceNix {
+			return true
+		}
 		log.Warnf("%s@%s not found in nixpkgs index, doing a source build. This may take some time...", tool.ToolName, tool.UnparsedVersion)
-		return false, nil
+		return false
 	}
 
-	return true, nil
+	return true
 }
 
 func (m *MiseToolProvider) installToolVersion(tool provider.ToolRequest) error {