assert with variables (#106)

* ok better errors

* can do vars in jq

* wip

* great

* Add Jamie Pond attribution to footer

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Move editor integration section near top of README

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Use lspconfig for neovim LSP setup instead of vim.lsp.config

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Address review feedback: extract truncateStr helper, add FindBareRefs tests, fix example line number

- DRY up duplicated truncation logic into a UTF-8-safe truncateStr helper
- Add table-driven tests for FindBareRefs covering bare refs, wrapped refs, edge cases
- Fix incorrect line number in bare-variable-warning example comment (18 → 25)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix lint: remove unused maxLen parameter from truncateStr

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* wip

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: jamierpond

README.md

@@ -59,6 +59,61 @@ make install
 
 -----
 
+## 🧠 Editor Integration (LSP)
+
+Unlike other API clients, **yapi** ships with a **full LSP implementation** out of the box. Your editor becomes an intelligent API development environment with real-time validation, autocompletion, and inline execution.
+
+### VS Code & Cursor
+
+Install the official extension from [VS Code Marketplace](https://marketplace.visualstudio.com/items?itemName=yapi.yapi-extension) or [Open VSX](https://open-vsx.org/extension/yapi/yapi-extension):
+
+**Features:**
+- **Run with `Cmd+Enter`** (Mac) or `Ctrl+Enter` (Windows/Linux) - execute requests without leaving your editor
+- **Inline results panel** - see responses, headers, and timing right in VS Code
+- **Real-time validation** - errors and warnings as you type
+- **Intelligent autocompletion** - context-aware suggestions for keys, methods, and variables
+- **Hover info** - hover over `${VAR}` to see environment variable status
+
+The extension automatically detects `.yapi.yml` files and activates the language server. No configuration needed.
+
+### Neovim (Native Plugin)
+
+**yapi** was built with Neovim in mind. First-class support via `lua/yapi_nvim`:
+
+```lua
+-- lazy.nvim
+{
+  dir = "~/path/to/yapi/lua/yapi_nvim",
+  config = function()
+    require("yapi_nvim").setup({
+      lsp = true,    -- Enables the yapi Language Server
+      pretty = true, -- Uses the TUI renderer in the popup
+    })
+  end
+}
+```
+
+Commands:
+- `:YapiRun` - Execute the current buffer
+- `:YapiWatch` - Open a split with live reload
+
+### Other Editors
+
+The LSP communicates over stdio and works with any editor that supports the Language Server Protocol:
+
+```bash
+yapi lsp
+```
+
+| Feature | Description |
+|---------|-------------|
+| **Real-time Validation** | Errors and warnings as you type, with precise line/column positions |
+| **Intelligent Autocompletion** | Context-aware suggestions for keys, HTTP methods, content types |
+| **Hover Info** | Hover over `${VAR}` to see environment variable status |
+| **Go to Definition** | Jump to referenced chain steps and variables |
+
+-----
+
 ## 🚀 Quick Start
 
 1.  **Create a request file** (e.g., `get-user.yapi.yml`):
@@ -161,6 +216,7 @@ chain:
 **Key features:**
 - Reference previous step data with `${step_name.field}` syntax
 - Access nested JSON properties: `${login.data.token}`
+- Use chain variables in assertions: `.id == ${previous_step.expected_id}`
 - Assertions use JQ expressions that must evaluate to true
 - Chains stop on first failure (fail-fast)
 
@@ -231,6 +287,29 @@ expect:
     - .[] | .active == true # all items are active
 ```
 
+**Chain variable assertions** - compare values across steps:
+
+```yaml
+yapi: v1
+chain:
+  - name: create_item
+    url: https://api.example.com/items
+    method: POST
+    body:
+      name: "Test Item"
+    expect:
+      status: 201
+
+  - name: get_item
+    url: https://api.example.com/items/${create_item.id}
+    method: GET
+    expect:
+      status: 200
+      assert:
+        - .id == ${create_item.id}           # verify same ID
+        - .name == "Test Item"
+```
+
 ### 5\. JQ Filtering (Built-in\!)
 
 Don't grep output. Filter it right in the config.
@@ -492,61 +571,6 @@ yapi test ./tests --verbose          # See server output
 
 -----
 
-## 🧠 Editor Integration (LSP)
-
-Unlike other API clients, **yapi** ships with a **full LSP implementation** out of the box. Your editor becomes an intelligent API development environment with real-time validation, autocompletion, and inline execution.
-
-### VS Code & Cursor
-
-Install the official extension from [VS Code Marketplace](https://marketplace.visualstudio.com/items?itemName=yapi.yapi-extension) or [Open VSX](https://open-vsx.org/extension/yapi/yapi-extension):
-
-**Features:**
-- **Run with `Cmd+Enter`** (Mac) or `Ctrl+Enter` (Windows/Linux) - execute requests without leaving your editor
-- **Inline results panel** - see responses, headers, and timing right in VS Code
-- **Real-time validation** - errors and warnings as you type
-- **Intelligent autocompletion** - context-aware suggestions for keys, methods, and variables
-- **Hover info** - hover over `${VAR}` to see environment variable status
-
-The extension automatically detects `.yapi.yml` files and activates the language server. No configuration needed.
-
-### Neovim (Native Plugin)
-
-**yapi** was built with Neovim in mind. First-class support via `lua/yapi_nvim`:
-
-```lua
--- lazy.nvim
-{
-  dir = "~/path/to/yapi/lua/yapi_nvim",
-  config = function()
-    require("yapi_nvim").setup({
-      lsp = true,    -- Enables the yapi Language Server
-      pretty = true, -- Uses the TUI renderer in the popup
-    })
-  end
-}
-```
-
-Commands:
-- `:YapiRun` - Execute the current buffer
-- `:YapiWatch` - Open a split with live reload
-
-### Other Editors
-
-The LSP communicates over stdio and works with any editor that supports the Language Server Protocol:
-
-```bash
-yapi lsp
-```
-
-| Feature | Description |
-|---------|-------------|
-| **Real-time Validation** | Errors and warnings as you type, with precise line/column positions |
-| **Intelligent Autocompletion** | Context-aware suggestions for keys, HTTP methods, content types |
-| **Hover Info** | Hover over `${VAR}` to see environment variable status |
-| **Go to Definition** | Jump to referenced chain steps and variables |
-
------
-
 ## 🌍 Environment Management
 
 Create a `yapi.config.yml` file in your project root to manage multiple environments:

apps/web/app/components/Landing.tsx

@@ -330,6 +330,7 @@ export default async function Landing() {
           <div className="flex gap-6">
             <a href="https://github.com/jamierpond/yapi" className="text-yapi-fg-subtle hover:text-yapi-accent transition-colors text-sm">Source Code</a>
             <a href="/docs" className="text-yapi-fg-subtle hover:text-yapi-accent transition-colors text-sm">Documentation</a>
+            <a href="https://pond.audio" target="_blank" rel="noopener noreferrer" className="text-yapi-fg-subtle hover:text-yapi-accent transition-colors text-sm">Created by Jamie Pond</a>
           </div>
         </div>
       </footer>

cli/internal/runner/runner.go

@@ -407,8 +407,12 @@ func RunChain(ctx context.Context, factory ExecutorFactory, base *config.ConfigV
 			logStepResponse(i+1, step.Name, result)
 		}
 
-		// 7. Assert Expectations
-		expectRes := CheckExpectationsWithEnv(step.Expect, result, opts.EnvOverrides)
+		// 7. Assert Expectations (with chain variable interpolation)
+		interpolatedExpect, err := interpolateExpectations(chainCtx, step.Expect)
+		if err != nil {
+			return nil, fmt.Errorf("step '%s': %w", step.Name, err)
+		}
+		expectRes := CheckExpectationsWithEnv(interpolatedExpect, result, opts.EnvOverrides)
 
 		// 8. Store Result (including expectation result even if failed)
 		chainCtx.AddResult(step.Name, result)
@@ -501,6 +505,38 @@ func warnBareChainRefsInConfig(stepName string, cfg *config.ConfigV1) {
 	}
 }
 
+// interpolateExpectations expands chain variables in assertion expressions.
+// This allows assertions like: .result.track_index == ${create_track.result.index}
+func interpolateExpectations(chainCtx *ChainContext, expect config.Expectation) (config.Expectation, error) {
+	result := expect
+
+	// Interpolate body assertions
+	if len(expect.Assert.Body) > 0 {
+		result.Assert.Body = make([]string, len(expect.Assert.Body))
+		for i, assertion := range expect.Assert.Body {
+			expanded, err := chainCtx.ExpandVariables(assertion)
+			if err != nil {
+				return result, fmt.Errorf("assertion '%s': %w", assertion, err)
+			}
+			result.Assert.Body[i] = expanded
+		}
+	}
+
+	// Interpolate header assertions
+	if len(expect.Assert.Headers) > 0 {
+		result.Assert.Headers = make([]string, len(expect.Assert.Headers))
+		for i, assertion := range expect.Assert.Headers {
+			expanded, err := chainCtx.ExpandVariables(assertion)
+			if err != nil {
+				return result, fmt.Errorf("header assertion '%s': %w", assertion, err)
+			}
+			result.Assert.Headers[i] = expanded
+		}
+	}
+
+	return result, nil
+}
+
 // interpolateConfig expands chain variables in a config
 func interpolateConfig(chainCtx *ChainContext, cfg *config.ConfigV1) (*config.ConfigV1, error) {
 	result := *cfg // Copy

cli/internal/utils/fn.go

@@ -1,5 +1,5 @@
 // Package utils provides generic utility functions.
-package utils
+package utils //nolint:revive // grab-bag utility package; no better name exists
 
 import (
 	"io"

cli/internal/utils/fn_test.go

@@ -1,4 +1,4 @@
-package utils
+package utils //nolint:revive // matches package declaration in fn.go
 
 import "testing"
 

cli/internal/validation/graphql_jq.go

@@ -9,6 +9,7 @@ import (
 	"github.com/itchyny/gojq"
 	"gopkg.in/yaml.v3"
 	"yapi.run/cli/internal/domain"
+	"yapi.run/cli/internal/vars"
 )
 
 // ValidateGraphQLSyntax validates the GraphQL query syntax if present.
@@ -130,11 +131,17 @@ func findFieldInNode(node *yaml.Node, field string) int {
 }
 
 // ValidateChainAssertions validates JQ syntax for all assertions in chain steps.
+// Chain variable references like ${step.field} are replaced with null before
+// parsing, since they'll be interpolated at runtime.
 func ValidateChainAssertions(text string, assertions []string, stepName string) []Diagnostic {
 	var diags []Diagnostic
 
 	for _, assertion := range assertions {
-		_, err := gojq.Parse(assertion)
+		// Replace ${...} chain variable refs with null for syntax validation
+		// These will be expanded at runtime before JQ evaluation
+		sanitized := vars.Expansion.ReplaceAllString(assertion, "null")
+
+		_, err := gojq.Parse(sanitized)
 		if err != nil {
 			// Find the line where this assertion appears
 			line := findValueInTextForAssertion(text, assertion)

examples/debugging/chain-var-in-assertion.yapi.yml

@@ -0,0 +1,27 @@
+# Demonstrates using chain variables in assertions.
+#
+# The second step's assertion compares a response value against
+# a value from the first step using ${step.field} syntax.
+#
+# Run with:
+#   yapi run chain-var-in-assertion.yapi.yml
+#
+# The assertion `.userId == ${get_todo.userId}` expands to `.userId == 1`
+# before being evaluated by JQ.
+
+yapi: v1
+chain:
+  - name: get_todo
+    url: https://jsonplaceholder.typicode.com/todos/1
+    method: GET
+    expect:
+      status: 200
+
+  - name: get_another_todo
+    url: https://jsonplaceholder.typicode.com/todos/2
+    method: GET
+    expect:
+      status: 200
+      assert:
+        # This todo also belongs to userId 1, so this should pass
+        - .userId == ${get_todo.userId}

integrations/nvim/lua/yapi_nvim/init.lua

@@ -175,12 +175,20 @@ function M.setup(opts)
 
   -- Setup LSP for yapi files
   if M._opts.lsp then
-    vim.lsp.config.yapi = {
-      cmd = { "yapi", "lsp" },
-      filetypes = { "yaml.yapi" },
-      root_markers = { "yapi.config.yml", "yapi.config.yaml", ".git" },
-    }
-    vim.lsp.enable("yapi")
+    local ok, lspconfig = pcall(require, "lspconfig")
+    if ok then
+      local configs = require("lspconfig.configs")
+      if not configs.yapi then
+        configs.yapi = {
+          default_config = {
+            cmd = { "yapi", "lsp" },
+            filetypes = { "yaml.yapi" },
+            root_dir = lspconfig.util.root_pattern("yapi.config.yml", "yapi.config.yaml", ".git"),
+          },
+        }
+      end
+      lspconfig.yapi.setup({})
+    end
 
     -- Set filetype to yaml.yapi for yapi config files
     vim.api.nvim_create_autocmd({ "BufReadPost", "BufNewFile" }, {