Add more env variable tests

cmd/pint/tests/0113_config_env_expand.txt

@@ -1,5 +1,6 @@
 env FOO=BAR
 env AUTH_KEY=1234
+env FAKE_ENV=KEY=VAL
 pint.ok --no-color config
 ! stdout .
 cmp stderr stderr.txt
@@ -64,7 +65,8 @@ level=info msg="Loading configuration file" path=.pint.hcl
         {
           "name": ".+",
           "keep": [
-            "BAR"
+            "BAR",
+            "KEY=VAL"
           ]
         }
       ]
@@ -86,6 +88,6 @@ rule {
       kind = "recording"
     }
     aggregate ".+" {
-        keep = [ "${ENV_FOO}" ]
+        keep = [ "${ENV_FOO}", "${ENV_FAKE_ENV}" ]
     }
 }

cmd/pint/tests/0114_config_env_expand_error.txt

@@ -0,0 +1,26 @@
+env FOO=BAR
+pint.error --no-color config
+! stdout .
+cmp stderr stderr.txt
+
+-- stderr.txt --
+level=info msg="Loading configuration file" path=.pint.hcl
+level=fatal msg="Fatal error" error="failed to load config file \".pint.hcl\": .pint.hcl:7,17-29: Unknown variable; There is no variable named \"ENV_AUTH_KEY\"., and 1 other diagnostic(s)"
+-- .pint.hcl --
+parser {
+  relaxed = [".*"]
+}
+prometheus "prod" {
+  uri = "http://localhost"
+  headers = {
+    X-Auth = "${ENV_AUTH_KEY}"
+  }
+}
+rule {
+    match {
+      kind = "recording"
+    }
+    aggregate ".+" {
+        keep = [ "${ENV_FOO}" ]
+    }
+}

internal/config/config.go

@@ -192,8 +192,8 @@ func (cfg *Config) GetChecksForRule(ctx context.Context, path string, r parser.R
 func getContext() *hcl.EvalContext {
 	vars := map[string]cty.Value{}
 	for _, e := range os.Environ() {
-		if i := strings.Index(e, "="); i >= 0 {
-			vars[fmt.Sprintf("ENV_%s", e[:i])] = cty.StringVal(e[i+1:])
+		if k, v, ok := strings.Cut(e, "="); ok {
+			vars[fmt.Sprintf("ENV_%s", k)] = cty.StringVal(v)
 		}
 	}
 	return &hcl.EvalContext{Variables: vars}